bluuebunny/crossref_metadata_2025 huggingface dataset:
A self-biased, low-frequency, miniaturized magnetoelectric antenna for implantable medical device applications
Authors: Mukherjee Dibyajyoti , Mallick Dhiman
Published: January 2023

Low-frequency (LF) magnetoelectric (ME) antennas are of great importance in implantable medical device (IMD) applications compared to their electromagnetic (EM) counterparts as they can potentially offer appropriate size miniaturization and lower path loss and higher efficiency. In this work, a self-biased, miniaturized LF ME antenna is proposed, which operates at its electromechanical resonant frequency of 49.9 kHz, with the size scaled down to only 1.75 mm3, which is significantly smaller than that of a comparable EM antenna. The proposed antenna that constitutes of a piezoelectric layer sandwiched between two magnetostrictive layers is characterized in both air and an optimized three-layered human tissue-mimicking phantom media to demonstrate the potential applications in deep-body communications. The near field radiation pattern of the ME antenna is measured experimentally. The maximum received power obtained at a distance of 1.2 m in air and phantom media is 20 and 8 nW, respectively. The proposed antenna has significantly lower path loss of 0.57 dB/m as compared to its higher frequency counterparts. Due to the lower path loss and smaller size, the proposed ME antenna can be suitable in several miniaturized IMD applications.
Study of MHD nanofluid flow with fuzzy volume fraction in thermal field-flow fractionation
Authors: Meher R. , Verma L. , Avazzadeh Z. , Nikan O.
Published: January 2023

This paper discusses the magnetohydrodynamic Jeffery–Hamel nanofluid flow (MHD-JHNF) between two rigid non-parallel plane walls. It enhances the study of simple Jeffery–Hamel flow problems to the MHD nanofluid flow problems with uncertain volume fractions. It examines the impact of various parameters, such as channel angles and Reynolds number with magnetic field and nanoparticles, on the fuzzy velocity profiles. The nanoparticle volume fraction is considered an uncertain parameter by using a triangular fuzzy number ranging from 0.0 to 0.2. A novel double parametric form-based homotopy analysis approach with its convergence analysis is introduced to examine the fuzzy velocity profiles at distinct convergent and divergent channel positions and fuzzy velocity boundaries at other channels and illustrates the efficiency of the process. Finally, Maple software is used to make the numerical simulations, and the results are checked with the available results for specific cases in crisp environments.
An enriched finite element/level-set model for two-phase electrohydrodynamic simulations
Authors: Narváez-Muñoz Christian , Hashemi Mohammad R. , Ryzhakov Pavel B. , Pons-Prats Jordi
Published: January 2023

In this work, a numerical model for the simulation of two-phase electrohydrodynamic (EHD) problems is proposed. It is characterized by a physically consistent treatment of surface tension as well as a jump in the electric material properties. The formulation is based on a finite element method enriched with special shape functions, capable of accurate capturing discontinuities both in the fluid pressure and the gradient of the electric potential. Phase interface is, thus, represented as a zero-thickness boundary. The proposed methodology allows modeling the electric force as an interfacial one, strictly abiding with the physics. The approach is tested using the droplet deformation benchmarks. Moreover, application of the method to study a three-dimensional (3D) case, not characterized by symmetry of revolution, is shown. The proposed methodology defines a basis for an enriched finite element method for a wide range of EHD problems.
Application of polarization imaging in counting plywood layers by machine vision
Authors: He Zhimin , Huang Cheng , Zeng Jun , Chen Fuchang , Yu Chaoqun , Li Yan , Lin Huichuan , Zhang Yongtao , Pu Jixiong
Published: January 2023

This paper introduces a machine vision system based on polarization imaging, which is applicable for automatically counting the number of internal layers in plywood. Industrial machine vision usually suffers from a low accuracy due to low contrast and high complexity of the images, which could be overcome by the introduction of polarization imaging. A polarization camera was utilized to capture images with polarization angles of 0°, 45°, 90°, and 135°, and then a degree of polarization (DOP) distribution image was obtained by calculating the DOP for each pixel. Compared with the intensity distribution image, the contrast of the DOP distribution image was increased by about 60% and the excessive information in the image including wood’s natural texture, dirty spots, dicing marks, and artifacts was mostly filtered. A gray value difference algorithm was applied to the images to determine the edges of the internal layers of plywood and count them up automatically. The experimental results illustrated that polarization imaging could improve the counting accuracy of the algorithm effectively.
Fourier-transform rheology and printability maps of complex fluids for three-dimensional printing
Authors: García-Tuñón Esther , Agrawal Rishav , Ling Bin , Dennis David J. C.
Published: January 2023

Direct ink writing (DIW) is a three-dimensional (3D) printing technique exploited by researchers working in fields from scaffolds for energy applications to bioprinting. DIW's main strength is that it enables shaping advanced materials, if these materials can be formulated into complex fluids that meet the demands of the printing process. They must be extremely shear thinning soft solids, able to flow through narrow nozzles, recovering their structure upon deposition and retaining the predesigned 3D shape. Formulation design and rheology are critical, but these aspects can be overlooked due to the high specialization required. This work provides insight on the rheology and printability of complex yield-stress fluids through the study of linear and nonlinear behaviors using large-amplitude oscillatory shear rheology. We refine previous protocols and develop tools to understand the behaviors of formulations for DIW. We apply an existing mathematical framework to a library of carbon-based formulations for energy applications. Fourier transform analysis enables quantifying the onset and rising of higher harmonic contributions. Quantitative comparisons between different formulations are established using 3D harmonics maps, stress–strain plots, and material measures of nonlinearities [Fourier and Chebyshev coefficients, elastic moduli (GM′, GL′), and dimensionless index of nonlinearity (S)]. 3D Lissajous plots provide a qualitative alternative to interpretate the yielding transition. We create Ashby-type printability maps to guide formulation design and elucidate that non-printable formulations show distinctive features. This insight on yield-stress fluids for DIW is relevant to other applications and technologies: drilling fluids, gels, colloids, and foods.
Particle dynamics due to interaction between a breaking-induced vortex and a nearbed vortex
Authors: Brocchini Maurizio , Marini Francesco , Falchi Massimo , Postacchini Matteo , Zitti Gianluca
Published: January 2023

One single regular wave, traveling over a submerged abrupt discontinuity, can generate a pair of counter-rotating vortices. A nearbed vortex is generated by the flow separation that occurs at the bed, while a surface vortex can be generated by either a direct (co-rotating vortex) or a backward (counter-rotating vortex) breaking. Starting from recent laboratory test results, which highlighted the role of wave nonlinearity on the interaction between the counter-rotating vortices and led to the identification of three different regimes [Brocchini et al., “Interaction between breaking-induced vortices and near-bed structures: Part 1—Experimental and theoretical investigation,” J. Fluid Mech. 940, A44 (2022)], the present work illustrates the main findings obtained from the optical analysis of the flow field induced by three different wave conditions, each belonging to a specific nonlinear regime. For each test, the measured domain has been seeded with virtual particles to obtain long-lasting trajectories driven by the Eulerian flow field recovered through the particle tracking velocimetry analysis, to be studied by means of single-particle and multi-particle statistics. Both absolute and relative statistics confirm that a ballistic regime exists just after particle release (t≲TL) at each location of the domain. At times larger than the Lagrangian timescale (t≳TL), the absolute statistics suggest a sub-diffusive regime both within the vortices and between such areas (i.e., in correspondence of the breaking-induced jet), followed by a superdiffusive regime, dominated by rotation and particle release. Differently, the relative diffusivity suggests the occurrence of a superdiffusive regime at t≳TL, corresponding to an enstrophy cascade and exponential growth, followed by a Richardson regime and then by an oscillatory behavior, during which particles are periodically trapped and released by vortices.
Key role of residual lead iodide in two-step processed perovskite layer for high performance perovskite solar cells
Authors: Li Jianfeng , Han Yaling , Jiang Weiwei , Huang Penghe , Cai Rui , Wang Minhuan , Bian Jiming
Published: January 2023

The delicate control of the crystallization behavior of the perovskite layer is critical for achieving high power conversion efficiency (PCE) and longer-term stability of perovskite solar cells (PSCs). Residual lead iodide (PbI2) was usually evitable in the two-step processed perovskite film due to incomplete reaction; however, its exact effects on the perovskite layer and resulting PSCs were not well elucidated so far. Here, the lead halide perovskite films were grown by the two-step process, where the residual PbI2 can be fine controlled by the concentration of organic salt solution. Results indicated that the properties of the perovskite layer may be varied greatly depending on the amount of residual PbI2, and a series of beneficial effects for PSCs can be achieved via suitable management of residue PbI2, i.e., prolonged carrier diffusion capacity, reduced defect density, inhibited ion migration, and interfacial charge recombination. Accordingly, an impressive PCE of 22.4% was achieved from the PSCs with optimized PbI2. Furthermore, the PSCs also displayed fairly good operational stability and retained 68% of its initial PCE after 400 h (at continuous irradiation under 1-sun illumination). This work may inspire solutions for further enhancing the performance of PSCs via fine controlled residual PbI2 in the perovskite layer.
A novel YAG:Ce/CsI:Tl phoswich detector consisting of transparent ceramic scintillator for α–γ discrimination
Authors: Qu Huan , Li Chengqian , Lu Jingbin , Wang H. D. , Li Ruopu , Kong Xiangduo , Liu Xinrui
Published: January 2023

Developing a ceramic scintillator operating in a phoswich detector is a feasible way for pulse shape discrimination. A YAG:Ce transparent ceramic scintillator has been synthesized by using the vacuum sintering method. In this work, we present a new phoswich detector mainly developed for the determination of low radioactivity levels. The system was constructed by combining a transparent ceramic scintillator, for the detection of α particles, and a CsI:Tl crystal, for the detection of γ-rays. With the device proposed here, the particle identification in a mixed α–γ field has been achieved with the rise time discrimination method. Furthermore, the figure of merit can also be improved using the phoswich detector. The higher reliability, simplicity, and low cost of the design that combines ceramics and crystals make the YAG ceramic have extremely good application prospects.
PESPIP: Software to fit complex molecular and many-body potential energy surfaces with permutationally invariant polynomials
Authors: Houston Paul L. , Qu Chen , Yu Qi , Conte Riccardo , Nandi Apurba , Li Jeffrey K. , Bowman Joel M.
Published: January 2023

We wish to describe a potential energy surface by using a basis of permutationally invariant polynomials whose coefficients will be determined by numerical regression so as to smoothly fit a dataset of electronic energies as well as, perhaps, gradients. The polynomials will be powers of transformed internuclear distances, usually either Morse variables, exp(−ri,j/λ), where λ is a constant range hyperparameter, or reciprocals of the distances, 1/ri,j. The question we address is how to create the most efficient basis, including (a) which polynomials to keep or discard, (b) how many polynomials will be needed, (c) how to make sure the polynomials correctly reproduce the zero interaction at a large distance, (d) how to ensure special symmetries, and (e) how to calculate gradients efficiently. This article discusses how these questions can be answered by using a set of programs to choose and manipulate the polynomials as well as to write efficient Fortran programs for the calculation of energies and gradients. A user-friendly interface for access to monomial symmetrization approach results is also described. The software for these programs is now publicly available.
Discretized hierarchical equations of motion in mixed Liouville–Wigner space for two-dimensional vibrational spectroscopies of liquid water
Authors: Takahashi Hideaki , Tanimura Yoshitaka
Published: January 2023

A model of a bulk water system describing the vibrational motion of intramolecular and intermolecular modes is constructed, enabling analysis of its linear and nonlinear vibrational spectra as well as the energy transfer processes between the vibrational modes. The model is described as a system of four interacting anharmonic oscillators nonlinearly coupled to their respective heat baths. To perform a rigorous numerical investigation of the non-Markovian and nonperturbative quantum dissipative dynamics of the model, we derive discretized hierarchical equations of motion in mixed Liouville–Wigner space, with Lagrange–Hermite mesh discretization being employed in the Liouville space of the intramolecular modes and Lagrange–Hermite mesh discretization and Hermite discretization in the Wigner space of the intermolecular modes. One-dimensional infrared and Raman spectra and two-dimensional terahertz–infrared–visible and infrared–infrared–Raman spectra are computed as demonstrations of the quantum dissipative description provided by our model.
Flow mechanism and heat transfer characteristic of sweeping jet impinging on confined concave surfaces
Authors: Tu Tianhong , Chen Shaowen , Shi Yuchen , Li Weihang
Published: January 2023

The sweeping jet actuator (SJA), a type of fluid oscillator, has attracted considerable attention in the areas of enhanced heat transfer and flow control. In this study, an unsteady Reynolds-averaged Navier–Stokes numerical investigation (k–ω baseline) was conducted to evaluate the flow mechanisms and heat transfer characteristics of a sweeping jet (SJ) on a confined concave surface. A conventional oscillating jet with a unit aspect ratio was used to generate the SJ. The heat transfer at the target surface and the flow details inside the flow field are discussed in detail to analyze the mechanism of the effect of SJ on impinging cooling. First, an appropriate numerical model was selected based on a comparison with a previous experiment. Subsequently, the time-averaged and time-resolved flow field and heat transfer results were investigated at three target distances for three different Reynolds numbers. The unsteady time-averaged results show that the SJ exhibits better heat transfer performance at higher Reynolds numbers and narrower target spacings than circle jet, which improves by 13% at Re = 30 000, H/D = 1. Subsequently, the turbulent kinetic energy and velocity loss theories were combined to compare the time-averaged and time-resolved flow field details of the two jets. The heat transfer characteristics of the target surface and the flow details inside the flow field in time and space were effectively correlated. Finally, the topology and three-dimensional (3D) vortex structure inside the confined channel were remodeled to better understand the unsteady sweeping process and provide theoretical support for subsequent applications.
A data-driven machine learning framework for modeling of turbulent mixing flows
Authors: Li Kun , Savari Chiya , Sheikh Hamzah A. , Barigou Mostafa
Published: January 2023

A novel computationally efficient machine learning (ML) framework has been developed for constructing the turbulent flow field of single-phase or two-phase particle-liquid flows in a mechanically agitated vessel by feeding a very short-term experimental Lagrangian trajectory. Using a supervised k-nearest neighbors regressor learning algorithm coupled with a Gaussian process, the framework predicts the mean flow and turbulent fluctuations by sharing the statistical features learned from experimental data. The capability of the ML framework is evaluated by comparing the flow dynamics of predicted trajectories to extensive Lagrangian particle tracking measurements under various flow conditions. Local velocity distributions, Lagrangian statistical analysis, solid concentration distributions, and phase flow numbers show very good agreement between ML-predictions and experiments. Being accurate, efficient, and robust, the ML framework is a powerful tool for analyzing and modeling multiphase flow systems using a minimal amount of driver data input, which can equally be provided from any reliable numerical simulation, thus avoiding costly experimental measurements.
Sheep grazing
Authors: Wilmot Matt G. , Norman Hayley C. , Hendry Joshua , Young Paul , Hulm Elizabeth , Toovey Andrew , Speijers Jane , Harrison Robert
Published: January 2023

Context An accession of the annual legume Trigonella balansae Boiss. & Reuter. has been selected for commercial release in Australia. Aims As part of a duty-of-care assessment, we tested the hypothesis that sheep grazing the trigonella accession will have liveweight, condition scores and wool production similar to those of sheep grazing two widely adopted annual legumes, subterranean clover (subclover, Trifolium subterraneum L. cv. Dalkeith) and French serradella (Ornithopus sativus Brot. cv. Erica). We also hypothesised that sheep grazing the three legumes will have similar meat quality and health, as indicated by blood plasma panel analysis. Methods Wethers (n = 6) grazed plots (n = 4) of three pasture species. Liveweight, condition scores and wool growth were measured, and a subset of animals were subject to blood sampling to assess health. Consumer sensory taste analysis was used to assess meat eating quality from two sheep per plot. Forage biomass, dry-matter digestibility, crude protein, fibre, mineral content and isoflavones were measured across the plant’s lifecycle. Key results There were no significant differences in liveweight, wool growth, wool yield or condition score that were associated with pasture species during the grazing period. There were differences in dry-matter digestibility, minerals and crude protein content of the pastures over time. As trigonella matured, it did not meet the minimum sulfur, phosphorus, manganese, molybdenum and copper requirements for mature sheep. We found some differences in indications of animal health; however, there were no significant systematic detrimental differences between sheep grazing trigonella and the other two species. In total, 2 of 24 individual sheep grazing trigonella had more than two plasma indicators of liver damage. There were no differences in meat tenderness, juiciness, flavour and overall consumer acceptability. Conclusions The data supported the hypotheses. Under the conditions of this experiment, the pasture legumes had the same relative feeding value. Some care must be taken in interpreting the outcome as the trigonellacomprised only 18% of the dry matter on offer at the termination of grazing. Implications Results of this study will be considered during the commercialisation process for T. balansae.
Structural basis of SecA-mediated protein translocation
Authors: Dong Linlin , Yang Song , Chen Jingxia , Wu Xiaofei , Sun Dongjie , Song Chen , Li Long
Published: January 2023

Secretory proteins are cotranslationally or posttranslationally translocated across lipid membranes via a protein-conducting channel named SecY in prokaryotes and Sec61 in eukaryotes. The vast majority of secretory proteins in bacteria are driven through the channel posttranslationally by SecA, a highly conserved ATPase. How a polypeptide chain is moved by SecA through the SecY channel is poorly understood. Here, we report electron cryomicroscopy structures of the active SecA–SecY translocon with a polypeptide substrate. The substrate is captured in different translocation states when clamped by SecA with different nucleotides. Upon binding of an ATP analog, SecA undergoes global conformational changes to push the polypeptide substrate toward the channel in a way similar to how the RecA-like helicases translocate their nucleic acid substrates. The movements of the polypeptide substrates in the SecA–SecY translocon share a similar structural basis to those in the ribosome–SecY complex during cotranslational translocation.
Inefficient exploitation of accessory receptors reduces the sensitivity of chimeric antigen receptors
Authors: Burton Jake , Siller-Farfán Jesús A. , Pettmann Johannes , Salzer Benjamin , Kutuzov Mikhail , van der Merwe P. Anton , Dushek Omer
Published: January 2023

Chimeric antigen receptors (CARs) can redirect T cells to target abnormal cells, but their activity is limited by a profound defect in antigen sensitivity, the source of which remains unclear. Here, we show that CARs have a > 100-fold lower antigen sensitivity compared to the T cell receptor (TCR) when antigen is presented on antigen-presenting cells (APCs) but nearly identical sensitivity when antigen is presented as purified protein. We next systematically measured the impact of engaging important T cell accessory receptors (CD2, LFA-1, CD28, CD27, and 4-1BB) on antigen sensitivity by adding their purified ligands. Unexpectedly, we found that engaging CD2 or LFA-1 improved the antigen sensitivity of the TCR by 125- and 22-fold, respectively, but improved CAR sensitivity by only < 5-fold. This differential effect of CD2 and LFA-1 engagement on the TCR vs. CAR was confirmed using APCs. We found that sensitivity to antigen can be partially restored by fusing the CAR variable domains to the TCR CD3
ε
subunit (also known as a TRuC) and fully restored by exchanging the TCR
α
β
variable domains for those of the CAR (also known as STAR or HIT). Importantly, these improvements in TRuC and STAR/HIT sensitivity can be predicted by their enhanced ability to exploit CD2 and LFA-1. These findings demonstrate that the CAR sensitivity defect is a result of their inefficient exploitation of accessory receptors and suggest approaches to increase sensitivity.
KIF1A is kinetically tuned to be a superengaging motor under hindering loads
Authors: Pyrpassopoulos Serapion , Gicking Allison M. , Zaniewski Taylor M. , Hancock William O. , Ostap E. Michael
Published: January 2023

KIF1A is a highly processive vesicle transport motor in the kinesin-3 family. Mutations in KIF1A lead to neurodegenerative diseases including hereditary spastic paraplegia. We applied optical tweezers to study the ability of KIF1A to generate and sustain force against hindering loads. We used both the three-bead assay, where force is oriented parallel to the microtubule, and the traditional single-bead assay, where force is directed along the radius of the bead, resulting in a vertical force component. The average force and attachment duration of KIF1A in the three-bead assay were substantially greater than those observed in the single-bead assay. Thus, vertical forces accelerate termination of force ramps of KIF1A. Average KIF1A termination forces were slightly lower than the kinesin-1 KIF5B, and the median attachment duration of KIF1A was >10-fold shorter than KIF5B under hindering loads. KIF1A rapidly reengages with microtubules after detachment, as observed previously. Strikingly, quantification enabled by the three-bead assay shows that reengagement largely occurs within 2 ms of detachment, indicating that KIF1A has a nearly 10-fold faster reengagement rate than KIF5B. We found that rapid microtubule reengagement is not due to KIF1A’s positively charged loop-12; however, removal of charge from this loop diminished the unloaded run length at near physiological ionic strength. Both loop-12 and the microtubule nucleotide state have modulatory effects on reengagement under load, suggesting a role for the microtubule lattice in KIF1A reengagement. Our results reveal adaptations of KIF1A that lead to a model of superengaging transport under load.
Regulatory T cells suppress CD4+ effector T cell activation by controlling protein synthesis
Authors: So Lomon , Obata-Ninomiya Kazushige , Hu Alex , Muir Virginia S. , Takamori Ayako , Song Jing , Buckner Jane H. , Savan Ram , Ziegler Steven F.
Published: January 2023

Regulatory T cells (Tregs) suppress the activation and subsequent effector functions of CD4 effector T cells (Teffs). However, molecular mechanisms that enforce Treg-mediated suppression in CD4 Teff are unclear. We found that Tregs suppressed activation-induced global protein synthesis in CD4 Teffs prior to cell division. We analyzed genome-wide changes in the transcriptome and translatome of activated CD4 Teffs. We show that mRNAs encoding for the protein synthesis machinery are regulated at the level of translation in activated CD4 Teffs by Tregs. Tregs suppressed global protein synthesis of CD4 Teffs by specifically inhibiting mRNAs of the translation machinery at the level of mTORC1-mediated translation control through concerted action of immunosuppressive cytokines IL-10 and TGFβ. Lastly, we found that the therapeutic targeting of protein synthesis with the RNA helicase eIF4A inhibitor rocaglamide A can alleviate inflammatory CD4 Teff activation caused by acute Treg depletion in vivo. These data show that peripheral tolerance is enforced by Tregs through mRNA translational control in CD4 Teffs.
Key comparison CCEM.RF-K27.W of RF power from 50 GHz to 75 GHz in rectangular waveguide
Authors: Cui Xiaohai , Yuan Wenze , Ding Sheng , Liu Xiaomeng , Liu Jinwen , Allal Djamel , Rühaak Jürgen , Kuhlmann Karsten , Tojima Yuya , Kinoshita Moto , Kwon Jae-Yong , Kang Tae-Weon , Perepelkin Vladimir A , Chirkov Igor P , Matveev Alexey I , Stokes Daniel , Hagerstrom Aaron M , Stelson Angela C , Jargon Jeffrey A , Gu Dazhen , Long Christian J , Ziadé François
Published: January 2023

Main text

This report summarizes the results of the measurements performed as a CIPM Key Comparison (CCEM.RF-K27.W) on high frequency power in waveguide among eight National Metrology Institutes (NMIs) of Germany (PTB), UK (NPL), France (LNE), China (NIM), Russia (VINIIFTRI), USA (NIST), Korea (KRISS), Japan (NMIJ). The Pilot Laboratory (PL) is NIM. The comparison was performed between May 2019 and December 2021. In this comparison, the effective efficiency and calibration factor of two WR15 (R620) waveguide thermistor mounts (travelling standards) were measured in the frequency range 50 GHz to 75 GHz. In the final report the list of participants, measurement quantities, methods of measurement, and measured results are given. The repeatability of the travelling standards, the key comparison reference values (KCRVs) and the degree of equivalence (DoE) of participating institutions are discussed. The appendix also provides the measurement method, measurement results and uncertainty budget of each participant. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Stability and numerical analysis of backward problem for subdiffusion with time-dependent coefficients
Authors: Zhang Zhengqi , Zhou Zhi
Published: January 2023

Our aim is to study the backward problem, i.e. recover the initial data from the terminal observation, of the subdiffusion with time dependent coefficients. First of all, by using the smoothing property of solution operators and a perturbation argument of freezing the diffusion coefficients, we show a stability estimate in Sobolev spaces, under some smallness/largeness condition on the terminal time. Moreover, in case of noisy data, we apply a quasi-boundary value method to regularize the problem and then show the convergence of the regularization scheme. Finally, we propose a completely discrete scheme by applying the finite element method in space and backward Euler convolution quadrature in time. An a priori error estimate is established. The proof is heavily built on a perturbation argument dealing with time dependent coefficients and some nonstandard error estimates for the direct problem. The error estimate gives an useful guide for balancing discretization parameters, regularization parameter and noise level. Some numerical experiments are presented to illustrate our theoretical results.
Fabrication of an X-shaped micro-copper structure containing a merging joint based on localized electrochemical deposition
Authors: Wang Fuliang , Pan Chengpeng , Tian Qiang , Hua Bingli
Published: January 2023

Local electrochemical deposition (LECD) has proved to be an efficient and economical method for fabricating three-dimensional micron structures. Realizing complex structures that join up when deposited using LECD has been complex; therefore, the fabrication of an X-shaped joining structure was investigated in this study. A horizontal trace model was proposed, and the effects of the number of deposition layers and the horizontal sweep width on the merging joint were studied. The horizontal trace model could complete the merging joint. Multiple deposition layers and a large horizontal sweep width could stabilize and better connect the X-shaped structure containing merging joints. The merging mechanism of the X-shaped structure was also investigated using COMSOL. The stable deposition of the joining structure enables the LECD method to have a broader range of applications in micro-nano manufacturing.
Induced flow inside a droplet by static electrical charge
Authors: Pradhan Tapan Kumar , Banuprasad Theneyur Narayanaswamy , Nandagopal M S Giri , Chakraborty Suman
Published: January 2023

Introducing controlled fluid motion in a droplet turns out to be of outstanding scientific importance, hallmarked by a plethora of applications ranging from engineering to biology. While internal mechanisms such as interfacial tension or buoyancy-driven dynamics may trigger fascinating flow structures inside a droplet, controllability of the same without external forcing remains questionable. On the other hand, in an electrically forced environment, complex fabrication steps and special choices of the ionic liquid are often demanded. Circumventing these limits, here we bring out a new method of flow manipulation inside a sessile droplet by simply deploying a static charge produced by the triboelectric effect. This is physically actuated by charge transfer between the two lateral electrodes within which the droplet is entrained, triggering a strong ionized air current. The flow inside the droplet is generated due to the shear exerted at the interface by the charge-induced ionized airflow around the droplet, a paradigm that has hitherto remained unexplored. The strength of the fluid flow can be controlled by adjusting the supplied static charge. Such unique controllability without sacrificing the physical simplicity opens up new possibilities for flow manipulation in a multitude of applications ranging from droplet microreactors to digital microfluidics.
Insights on film growth conditions on a floating substrate during reactive Ar/O2 bipolar high power impulse magnetron sputter deposition
Authors: Michiels M , Britun N , Caillard A , Thomann A-L , Snyders R , Konstantinidis S
Published: January 2023

We report several effects found in reactive bipolar high-power impulse magnetron sputtering (abbreviated as bipolar HiPIMS or BPH) discharges at the substrate level. The role of the negative peak current and the positive pulse voltage, U

+

, on the deposition flux at the electrically insulating substrate is discussed and the results are compared to conventional DC discharges. In particular, the normalized energy flux, ϕ

n
, delivered to the substrate is found higher under BPH conditions at U

+

= +300 V (

φ
n

=
3.43
×

10

15

eV·nm−3) as compared to the HiPIMS (

φ
n

=
0.78
×

10

15

eV·nm−3) and DCMS (

φ
n

=
1.23
×

10

15

eV·nm−3) regimes which is assumed to be provoked by an intensification of the positive ion bombardment. Accordingly, the mean energy and the count of positively charged metal and gaseous ions increase in line with U

+

as measured by energy-resolved mass spectrometry. Contrariwise, our analysis has shown a significant decrease (≈20 %) of negative oxygen ion count under BPH conditions.
Facets of reaction mechanism in 6Li+181Ta system
Authors: Kumar Rishabh , Prajapat Rinku , Maiti Moumita
Published: January 2023

More focused investigations are required to better understand the different modes of fusion phenomena in weakly bound projectiles. In order to comprehend the reaction mechanism of weakly bound projectiles, a new measurement of the evaporation residue cross sections from the 6Li-induced reaction on 181Ta in the 4.5–7.1 MeV/nucleon energy range has been reported in this article. The γ-ray spectrometry has been employed to identify the 183m,g
Os, 182Os, 183Re, and 183,182m2,180Ta residues produced in the reaction via different evaporation channels. The EMPIRE-3.2.2 code, which houses both the equilibrium and pre-equilibrium models in its framework, and PACE4 have been tasked to analyze the measured excitation functions. Out of the two, EMPIRE-3.2.2 demonstrates better agreement with the data. A systematic analysis of the measured data and theoretical background indicates that the complete and incomplete fusion of 6Li contribute to the residual cross sections. Thus, the strength of the partial fusion has been inferred. Further, the neutron transfer channels have been found to contribute significantly to the reaction dynamics; hence they are investigated using the coupled reaction channel calculations and discussed in detail. The isomeric cross section ratio obtained from the measured residual cross sections of the isomeric pair of 183Os highlights the significance of angular momentum and relative spins of the ground and isomeric states as a function of projectile incident energy.
Machine learning approach to study quantum phase transitions of a frustrated one dimensional spin-1/2 system
Authors: Rahaman Sk Saniur , Haldar Sumit , Kumar Manoranjan
Published: January 2023

Frustration-driven quantum fluctuation leads to many exotic phases in the ground state (GS) and the study of these quantum phase transitions is one of the most challenging areas of research in condensed matter physics. We study a frustrated Heisenberg

J
1

−

J
2

model of spin-1/2 chain with nearest exchange interaction J
1 and next nearest exchange interaction J
2 using the principal component analysis (PCA) which is an unsupervised machine learning technique. In this method most probable spin configurations (MPSCs) of GS and first excited state (FES) for different

J
2

/

J
1

are used as the input in PCA to construct the covariance matrix. The ‘quantified principal component’

p
1

(

J
2

/

J
1

)

of the largest eigenvalue of the covariance matrix is calculated and it is shown that the nature and variation of

p
1

(

J
2

/

J
1

)

can accurately predict the phase transitions and degeneracies in the GS. The

p
1

(

J
2

/

J
1

)

calculated from the MPSC of GS only exhibits the signature of degeneracies in the GS, whereas,

p
1

(

J
2

/

J
1

)

calculated from the MPSC of FES captures the gapless spin liquid (GSL)-dimer phase transition as well as all the degeneracies of the model system. We show that the jump in

p
1

(

J
2

/

J
1

)

of FES at

J
2

/

J
1

≈
0.241

, indicates the GSL-dimer phase transition, whereas its kinks give the signature of the GS degeneracies. The scatter plot of the first two principal components of FES shows distinct band formation for different phases. The MPSCs are obtained by using an iterative variational method (IVM) which gives the approximate eigenvalues and eigenvectors.
Evidence of electron correlation and weak bulk plasmon in SrMoO3
Authors: Ali Asif , Reddy B H , Singh Ravi Shankar
Published: January 2023

We investigate the electronic structure of highly conducting perovskite SrMoO3 using valence band photoemission spectroscopy and electronic structure calculations. Large intensity corresponding to coherent feature close to Fermi level is captured by density functional theory (DFT) calculation. An additional satellite at ∼3 eV binding energy remains absent in DFT, hybrid functional (DFT-hybrid) and dynamical mean field theory (DFT + DMFT) calculations. Mo 4d spectra obtained with different surface sensitive photoemission spectroscopy suggest different surface and bulk electronic structures. DFT + DMFT spectral function is in excellent agreement with the coherent feature in the bulk Mo 4d spectra, revealing moderate electron correlation strength. A large plasmon satellite and signature of strong electron correlation are observed in the surface spectra, while the bulk spectra exhibits a weak plasmon satellite.
Radiation safety of current European practices of therapeutic nuclear medicine: survey results from 20 HERCA countries
Authors: Bly Ritva
Published: January 2023

The purpose of this study was to acquire up-to-date information on nuclear medicine treatments in Europe and on the implementation of the requirements of the Basic Safety Standards Directive in HERCA Heads of the European Radiological Protection Competent Authorities (HERCAs) member states. An electronic survey was distributed to competent authorities of 32 HERCA member states. The questionnaire addressed 33 explicitly considered treatments using 13 different radionuclides, and for each treatment, a similar set of questions was included. Questions covered the use of treatments, hospitalisation of patients and radioactive waste management related to therapeutic nuclear medicine involving other radionuclides than the well-known 131I. The survey also covered justification of treatments, individual treatment planning, involvement of a medical physics expert (MPE) and radiation protection instructions given to the patient at the time of release. Responses were obtained from 20 HERCA countries. All of these countries used Na[131I]I for benign thyroid diseases and thyroid ablation of adults. 223RaCl2 (Xofigo®) for bone metastases, 177Lu-somatostatin analogues for neuroendocrine tumours and 177Lu-labelled PSMA for castration resistant prostate cancer (PC) and PC-metastases were used in 90%, 65% and 55% of countries, respectively. Only a few countries had specific criteria for hospitalisation and waste management for new therapeutic nuclear medicine. Regulatory requirements for justification of new therapeutic nuclear medicine were in place in almost all countries. Individual treatment planning was required for all therapies in 55% and for some therapies in 28% of the responding countries. Implementation of the requirement for MPEs to be closely involved in nuclear medicine practices varied to a great extend among countries. Almost all responding countries answered that some radiation protection instructions existed for patients released after treatment with radionuclides other than 131I treatment, however only few countries had developed specific guidelines in the field.
A method for rolling bearing fault diagnosis based on GSC-MDRNN with multi-dimensional input
Authors: Wang Zheng , Wen Chuanbo , Dong Yifan
Published: January 2023

The traditional fault diagnosis methods for rolling bearings through neural networks mostly use data sources collected by a single sensor and use single-dimensional data input, leading to fault features in bearings not be completely extracted. Moreover, traditional convolution often uses single-size convolution kernels, which are insufficient for fault feature extraction. In response to these problems, the global shortcut connection (GSC)-multichannel deep ResNet network model is proposed. First, a new residual structure, the GSC, is proposed to fuse two-dimensional and one-dimensional signal features. Second, involution is introduced into the field of fault diagnosis to address the problem of insufficient network feature extraction caused by using single-size convolution kernels. In addition, a convolutional block attention module can adaptively assign the weight of each channel feature to achieve adaptive channel fusion. The verification was performed on the four-category and eight-category data sets collected in the laboratory, and the results show that this method has a high fault recognition rate.
Flame stability measurement through image moments and texture analysis
Authors: Golgiyaz Sedat , Cellek M Salih , Daskin Mahmut , Talu M Fatih , Onat Cem
Published: January 2023

In this article, the first two moments of the image, mean and standard deviation, uniform local binary pattern (LBP) texture analysis methods were experimentally investigated in coal-fired boilers to measure flame stability. The first two moments of the flame image were used to evaluate the flame stability in terms of color and brightness (average gray value). Although the radiation signal of the flame is widely obtained by the spectral analysis method, the radiation signal of the flame was obtained by the LBP texture analysis method in this study. The flame stability measurement technique proposed in this study does not require prior knowledge about charged coupling devices camera features. Therefore, it can be easily applied to measure flame stability without expensive and complicated adaptation processes. Flame stability was measured with R = 0.9868 accuracy with the proposed method. The experimental results show that the proposed texture analysis method is more effective than current spectral analysis methods. The results obtained within the scope of this study also show that it can be easily applied to existing closed-loop control systems to monitor flame stability.
Controlling thermal noise in phase-field simulation for nucleation during isothermal solidification of a pure metal
Authors: Yamada Ryo , Haraguchi Keisuke , Ohno Munekazu
Published: January 2023

It is currently challenging to quantitatively describe the nucleation behavior using the phase-field model because it depends on the computational grid size. In this study, the grid size dependence of nucleation behavior during isothermal solidification in pure Fe was investigated by changing the magnitude of thermal noise inducing the nucleation. To remove such dependence, a neural network was utilized to compute the magnitude of thermal noise needed to describe the desired nucleation rate for a given grid size and degree of undercooling. It was found that the nucleation rate can be controlled using the present approach, and the nucleation rates in pure Fe obtained by molecular dynamics simulations and experiments could be accurately reproduced.
Internal-wave billiards in trapezoids and similar tables
Authors: Lenci Marco , Bonanno Claudio , Cristadoro Giampaolo
Published: January 2023

We call internal-wave billiard the dynamical system of a point particle that moves freely inside a planar domain (the table) and is reflected by its boundary according to this nonstandard rule: the angles that the incident and reflected velocities form with a fixed direction (representing gravity) are the same. These systems are point particle approximations for the motion of internal gravity waves in closed containers, hence the name. For a class of tables similar to rectangular trapezoids, but with the slanted leg replaced by a general curve with downward concavity, we prove that the dynamics has only three asymptotic regimes: (1) there exist a global attractor and a global repellor, which are periodic and might coincide; (2) there exists a beam of periodic trajectories, whose boundary (if any) comprises an attractor and a repellor for all the other trajectories; (3) all trajectories are dense (that is, the system is minimal). Furthermore, in the prominent case where the table is an actual trapezoid, we study the sets in parameter space relative to the three regimes. We prove in particular that the set for (1) has positive measure (giving a rigorous proof of the existence of Arnol’d tongues for internal-wave billiards), whereas the sets for (2) and (3) are non-empty but have measure zero.
Disruption avoidance by stabilizing coupled MHD modes using resonant magnetic perturbations on J-TEXT
Authors: He Ying , Wang Nengchao , Ding Yonghua , Li Da , Zhou Song , Mao Feiyue , Shen Chengshuo , Jia Ruo , Ren Zhengkang , Gao Yuan , Zhang Zhichao , Li Shuhao , Huang Zhuo , Chen Haojie , Zhao Chuanxu , Bala Abba Alhaji , Zhang Wei , Xie Xianli , Chen Zhipeng , Yang Zhoujun , Chen Zhongyong , Yu Q , Pan Yuan
Published: January 2023

The coupling of multiple magnetohydrodynamic (MHD) modes can lead to mode locking and major disruption in tokamak plasmas. In the J-TEXT tokamak, the coupling between two small modes, i.e. m/n = 2/1 and 3/1 modes (m and n are poloidal and toroidal mode numbers, respectively), appears when the edge safety factor is reduced to the vicinity of 3. After the mode coupling, the toroidal phase difference between the 2/1 and 3/1 modes equals 0 in the low field side midplane. This phase relation of coupled modes leads to mutual destabilization and even major disruption. A control scheme to avoid disruption caused by coupled modes by resonant magnetic perturbations (RMPs) is presented. It is found that the application of RMP significantly changes the evolution of the coupled modes. The coupling of the 2/1 and 3/1 modes occurs earlier as the RMP amplitude increases. The RMP with moderate amplitude can suppress the growth of 2/1 and 3/1 coupled modes and hence avoid disruption. These results provide a possible strategy for the suppression of neoclassical tearing mode (NTM) seed islands on International Thermonuclear Experimental Reactor (ITER) or future fusion reactors.
Invention of smart tightening tool for directly controlling the preload of bolted joints
Authors: Zhang Zhongwei , Liu Jianhua , Gong Hao , Huang Jiayu , Du Chenfei , Liu Kai , Cao Linlin
Published: January 2023

Bolted joints are widely used in industries to connect and fasten two separated components. During the assembly of bolted joints, torque wrench is commonly employed to control preload indirectly. Much scatter in preload will occur and decrease the reliability of mechanical product. This study invented a novel tightening tool, which could directly control preload with high accuracy in the process of tightening bolts. The novel tightening tool is composed of an ameliorative intelligent wrench and signal processing system. There are two characteristics or innovations in the intelligent wrench. First, an electric tripping structure with multi-level small-size lever is designed to ensure that the target preload can be controlled effectively when the threshold value is reached. Second, an intelligent socket integrated with PZT sensor is designed, which can avoid many PZT sensors being sticked on bolt heads and greatly reduce cost. In the signal processing system, the waveform tracking strategy based on phase-locked loop is proposed to obtain the stable phase difference, which improves the robustness of the calculation of echo time. Three types of bolts with different sizes were tested. The average preload error was approximatively 2%, validating the accuracy and effectiveness of our tightening tool.