bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study on energy harvesting maximization from the flow-induced vibration of a highly confined bluff body
Authors: Sanchez-de-Leon Luis , Sastre Francisco , Barrero-Gil Antonio , Velazquez Angel
Published: August 2023

Flow-induced vibrations of rigid prisms supported elastically were studied experimentally in a free-surface water channel with a high blockage (2/5). The study focused on finding the prism cross-sectional shape that maximizes the efficiency of energy harvesting. Seven cross-sectional shapes were tested: square, circular, 45° tilted square, equilateral triangle, isosceles 120° triangle, D-section, and C-section. All other dimensionless parameters of the problem, mass ratio, damping, blockage ratio, reduced velocity range, and the Reynolds (Re) number (characteristic velocity times characteristic length divided by kinematic viscosity) range (400–1070), were kept unchanged. By doing so, the effect of the cross-sectional shape was isolated. D-section proved to be the geometry with the highest values of energy transfer efficiency. A hysteresis loop was present in its oscillatory response (dimensionless oscillation amplitude vs reduced velocity). This loop was characterized by two branches, (+) and (−), meaning a bi-valued amplitude response for each reduced velocity. Regarding temporal patterns of wake topology and body motion, it was found that synchronization occurs in the (+) branch, but not in the (−). Regarding vortex shedding modes, particle image velocimetry was used for identification purposes, and it was found that the 2P mode is the dominant mode in the (+) branch, while the 2S mode pervades the (−). Finally, a new relative reduced velocity definition was introduced, and, when re-plotting the experimental results, it was found that the hysteresis loop disappears, thereby providing a more compact mathematical description of the observed phenomena.
Surface entrapment of micromotors by a background temperature field
Authors: Damor Himanshu , Ghosh Soumyajit , Poddar Antarip
Published: August 2023

The fabrication of self-propelling micromotors and the study of their propulsion strategies have gained attention due to their wide range of applications in the medical, engineering, and environmental fields. The role of a background temperature field in the precise navigation of a self-thermophoretic micromotor near an insulated wall has been investigated by employing exact solutions to the energy equation and creeping flow. We report bound states for half-coated micromotors appearing as steady-state sliding, damped, and periodic oscillations when the dimensionless external temperature gradient (S) is in the range of 0.15≤S<0.26. The sliding height is lower with S but remains insensitive to the thermal conductivity contrast. Moreover, the stationary states for the self-propelled, asymmetrically coated micromotors transform into scattering trajectories. We highlight the combinations of S and coating coverage needed for guided swimming up or against the field along with a broad spectrum of counter-intuitive temporal variations of its navigating locations. These unique observations have been ascribed to a confinement-mediated dynamic coupling between the passive and active propulsion mechanisms.
External concentration gradients can drive a propagating wave in a coherently layered system of nanosheets
Authors: Brand Helmut R. , Pleiner Harald
Published: August 2023

We present a model for the dynamics observed recently by Sano et al. [Nat. Commun. 12, 6771 (2021)] in a coherently layered system made up of sheetlike colloidal particles (nanosheets) subjected to an external concentration gradient. Adding a new macroscopic variable characteristic for the nonequilibrium situation encountered in the experiments to the hydrodynamics of smectic A liquid crystals, we show that all salient dynamic features observed in the experiments can be accounted for. For this nonequilibrium phenomenon, we identify the symmetry of the underlying ground state as undulating smectic A-like layering and the applied concentration gradient applied in the layer planes as the nonequilibrium driving force. As a result of our analysis, we find a coherent motion of undulating layers generated by a Helfrich–Hurault type instability propagating at a fixed velocity in accordance with the observations. If the coherence of the layering is lost, there is no longer any coherent propagation to be expected—as is also observed.
Investigation on a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells
Authors: Peng Tao , Qiang Jun , Yuan Shuai
Published: August 2023

High-precision and high-purity acquisition of tumor cells from whole blood is vital for early disease detection and diagnosis. Here, we investigated a cascaded inertial and acoustic microfluidic device for sheathless and label-free separation of circulating tumor cells (CTCs) from the blood through numerical methods. We introduced a spiral microfluidics channel in the first stage (1st) for cell focusing and rough sorting to improve chip integration and reduce the dependence on sheath flow and extra syringe pumps. In the 1st, we simulated the spiral microfluidic with a rectangular cross section to determine the key parameters affecting the migration kinetics of blood cells and tumor cells. Under the influence of Dean drag force and inertial lift force, blood cells migrate toward the inner side of the channel, while CTCs flow out close to the outer side. A flow rate of 400 μl/min was optimized for the operating flow rate. To improve and further enhance the 1st sorting efficiency and purity, we introduced tilted angle standing surface acoustic wave (SSAW) in the second stage (2st). Based on the parametric study, the SSAW with 33.3 MHz, tilted angle with 5°, and acoustic pressure amplitude with 0.7 MPa was selected as the operating parameter. The product of the 1st is used as input for the 2st acoustofluidic unit, enabling a more accurate separation process to obtain CTCs. The simulation results show that the inertial microfluidic units arranged in the first stage help to improve throughput and assist in 2st acoustofluidic separation, and the cascaded chip has accomplished a separation performance of nearly 100% in terms of purity and efficiency.
Experimental and numerical studies of piston-mode resonance in a three-dimensional circular moonpool
Authors: Han Jian , Zhang Xinshu , Huang Haiyang
Published: August 2023

We develop a modified potential flow model (MPFM) for a circular moonpool by quantifying the viscous damping. The flow-separation-induced damping coefficients of MPFM do not need to be tuned by the users as they are derived from the conduit problem studied by Idelchik, where the variation of such coefficients with geometry configurations is given based on experiments. To verify the MPFM, we conducted laboratory experiments in heave radiation (forced harmonic heave motion) and wave diffraction (fixed in regular wave) problems with a broad range of frequencies and compared the results with those of MPFM and a boundary element method without viscosity modeling (BEM). The MPFM achieves fairly good agreement with the experimental results, including those around the resonance frequency where BEM over-predicts. A simple time-domain model is developed to analyze the sources of the different harmonics in the free-surface elevation observed in the experiment.
Toxicity of trimethoprim towards marine microalgae: implication for environmental risk assessment
Authors: Duan Weiyan , Su Bo , Feng Pengfei , Zhang Chan , Du Liqin , Wu Jiangyue
Published: August 2023

Context Trimethoprim (TMP) is a common antibacterial medication used in human and veterinary medicine, including in aquaculture. Antibiotic misuse and abuse results in the antibiotic pollution of water and has attracted increasing attention. Antibiotics are frequently detected in water bodies and pose a certain environmental risk to the aquatic system. Aims Two marine diatoms, i.e. Phaeodactylum tricornutum and Skeletonema costatum, were tested for toxicity to better understand the ecological implications of TMP in the marine system. Methods The routine static toxicity test method for microalgae was selected to be used. Key results The 96-h median effective concentration (EC50) values based on average specific growth rate (96-h ErC50) were >1.000 and >5.000 mg L−1 for P. tricornutum and S. costatum respectively. Conclusions P. tricornutum was more sensitive than S. costatum in its exposure to TMP, with a no observation-effect concentration (NOEC) value of 0.063 mg L−1. On the basis of the risk data, TMP poses a great risk to the aquatic system in certain countries. Implications The results of this study provide a better understanding of the potential ecological risks of TMP in the marine environment.
The role of grass-tree Xanthorrhoea semiplana (Asphodelaceae) canopies in temperature regulation and waterproofing for ground-dwelling wildlife
Authors: Petit Sophie , Frazer Deborah S.
Published: August 2023

Context The iconic grass-trees (Xanthorrhoea semiplana) of Australia are used by many animal species, but their role as shelters against weather extremes is poorly known. The severe contribution of the fungal pathogen Phytophthora cinnamomi to grass-tree deaths and current burning practices could affect small animal conservation by exacerbating impacts of weather extremes. Aims We examined the buffering role of X. semiplana canopies against extreme weather at four sites in the Mount Lofty Ranges, South Australia. Methods We measured ambient temperature, temperatures under grass-tree canopies, and 2 m away at random locations in summer (>35°C) and in winter (<13°C) over 24-h periods at each study site. We scored soil dryness under the canopies during and after heavy rainfall. Key results Temperatures under grass-tree canopies were more stable and with smaller ranges than other temperatures, and showed dramatic differences in summer when conditions were up to 20°C cooler than ambient. Temperatures were higher under grass-trees at night in winter. The soil under the largest canopies was completely dry during and after heavy rainfall. Conclusions Xanthorrhoea semiplana buffers ground-dwelling animals against temperature extremes and rain so that the animals maintain their thermal resistance. Animals may choose foraging times based on grass-tree availability. The largest grass-trees provide the best shelter. Implications Considerable grass-tree deaths from P. cinnamomi infestation, together with removal or burning, can have dramatic detrimental consequences for their habitat value and the survival of wildlife using them as shelter.
Reversal of an existing hearing loss by gene activation in
Spns2
mutant mice
Authors: Martelletti Elisa , Ingham Neil J. , Steel Karen P.
Published: August 2023

Hearing loss is highly heterogeneous, but one common form involves a failure to maintain the local ionic environment of the sensory hair cells reflected in a reduced endocochlear potential. We used a genetic approach to ask whether this type of pathology can be reversed, using the

Spns2
tm1a

mouse mutant known to show this defect. By activating
Spns2
gene transcription at different ages after the onset of hearing loss, we found that an existing auditory impairment can be reversed to give close to normal thresholds for an auditory brainstem response (ABR), at least at low to mid stimulus frequencies. Delaying the activation of
Spns2
led to less effective recovery of ABR thresholds, suggesting that there is a critical period for intervention. Early activation of
Spns2
not only led to improvement in auditory function but also to protection of sensory hair cells from secondary degeneration. The genetic approach we have used to establish that this type of hearing loss is in principle reversible could be extended to many other diseases using available mouse resources.
An oncolytic virus–delivered TGFβ inhibitor overcomes the immunosuppressive tumor microenvironment
Authors: DePeaux Kristin , Rivadeneira Dayana B. , Lontos Konstantinos , Dean Victoria G. , Gunn William G. , Watson McLane J. , Yao Tianhong , Wilfahrt Drew , Hinck Cynthia , Wieteska Lukasz , Thorne Stephen H. , Hinck Andrew P. , Delgoffe Greg M.
Published: August 2023

While checkpoint blockade immunotherapies have widespread success, they rely on a responsive immune infiltrate; as such, treatments enhancing immune infiltration and preventing immunosuppression are of critical need. We previously generated αPD-1 resistant variants of the murine HNSCC model MEER. While entirely αPD-1 resistant, these tumors regress after single dose of oncolytic vaccinia virus (VV). We then generated a VV-resistant MEER line to dissect the immunologic features of sensitive and resistant tumors. While treatment of both tumor types induced immune infiltration and IFNγ, we found a defining feature of resistance was elevation of immunosuppressive cytokines like TGFβ, which blunted IFNγ signaling, especially in regulatory T cells. We engineered VV to express a genetically encoded TGFβRII inhibitor. Inhibitor-expressing VV produced regressions in resistant tumor models and showed impressive synergy with checkpoint blockade. Importantly, tumor-specific, viral delivery of TGFβ inhibition had no toxicities associated with systemic TGFβ/TGFβR inhibition. Our data suggest that aside from stimulating immune infiltration, oncolytic viruses are attractive means to deliver agents to limit immunosuppression in cancer.
Geometric Thermoelectric Pump: Energy Harvesting beyond Seebeck and Pyroelectric Effects
Authors: Ren Jie
Published: August 2023

Thermal-electric conversion is crucial for smart energy control and harvesting, such as thermal sensing and waste heat recovering. So far, researchers are aware of two main ways of direct thermal-electric conversion, Seebeck and pyroelectric effects, each with different working mechanisms, conditions and limitations. Here, we report the concept of Geometric Thermoelectric Pump (GTEP), as the third way of thermal-electric conversion beyond Seebeck and pyroelectric effects. In contrast to Seebeck effect that requires spatial temperature difference, GTEP converts the time-dependent ambient temperature fluctuation into electricity. Moreover, GTEP does not require polar materials but applies to general conducting systems, and thus is also distinct from pyroelectric effect. We demonstrate that GTEP results from the temperature-fluctuation-induced charge redistribution, which has a deep connection to the topological geometric phase in non-Hermitian dynamics, as a consequence of the fundamental nonequilibrium thermodynamic geometry. The findings advance our understanding of geometric phase induced multiple-physics-coupled pump effect and provide new means of thermal-electric energy harvesting.
Simple Python tools for modelling few-level atom-light interactions
Authors: Downes Lucy
Published: August 2023

Understanding the interactions between atoms and light is at the heart of atomic physics. Being able to ‘experiment’ with various system parameters, produce plots of the results and interpret these is very useful, especially for those new to the field. This tutorial aims to provide an introduction to the equations governing near-resonant atom-light interactions and present examples of setting up and solving these equations in Python. Emphasis is placed on clarity and understanding by showing code snippets alongside relevant equations, and as such it is suitable for those without an excellent working knowledge of Python or the underlying physics. Hopefully the methods presented here can form the foundations on which more complex models and simulations can be built. All functions presented here and example codes can be found on GitHub.
Two magnetic entropy peaks during one-step martensitic transformation in a Ni42Co8Mn37.5In12.5 alloy
Authors: Wu Xiaokang , Cheng Fei , Wang Jiaotong , Guo Yuanjun , Jiang Runxiang , Zheng Aqun , Bi Pengfei , Sun Hao , Wang Yu
Published: August 2023

Magnetic shape memory alloys with multiple entropy change (ΔSM
) peaks are promising to extend the working temperature window (ΔT
eff) in active magnetic refrigeration. They usually have multi-step martensitic transformations, since the multiple variations of structure and magnetic states lead to the one-to-one corresponding ΔSM
peaks. In this work, we report an interesting Ni42Co8Mn37.5In12.5 magnetocaloric alloy, which exhibits only one-step martensitic transformation but generates two considerable ΔSM
peaks with the value of 7.2 J K−1 kg−1 and 9.9 J K−1 kg−1 under 6 T respectively. This phenomenon is attributed to the restriction internal stresses stemming from the lattice mismatch between martensite and austenite, the random local stresses produced by defects, the interfacial hindrances of wide phase boundaries, and the inhibition of dispersed precipitates, which divide the one-step transformation into two discrete stages. Such multiple ΔSM
peaks are beneficial for expanding the working temperature window of magnetocaloric refrigerators.
Ferroelectric source follower for voltage-sensing nonvolatile memory and computing-in-memory
Authors: Toprasertpong Kasidit , Matsui Chihiro , Takenaka Mitsuru , Takeuchi Ken , Takagi Shinichi
Published: August 2023

Memory arrays and computing-in-memory architecture based on emerging nonvolatile memory devices with a current-sensing scheme face several challenges when implemented in large-scale arrays, such as power and area penalties, voltage drop, and power-source limitations. Here, we demonstrate ferroelectric source followers as nonvolatile memory devices operating with a voltage-sensing scheme. The voltage output read out from the source terminal of a ferroelectric field-effect transistor is determined in a nonvolatile manner by the polarization state stored in a ferroelectric gate insulator, giving a higher output voltage at a lower threshold voltage. Device modeling reveals that the output voltage is described by a simple expression of the threshold voltage, gate bias, drain bias, and body-effect factor. Simple characteristics, low readout energy consumption (∼fJ) owing to an absence of steady current, and fast readout operation (∼ns) make ferroelectric source followers promising for voltage-sensing nonvolatile memory and voltage-sensing synapse as well as activation functions (biased rectified linear units) in computing-in-memory.
Experimental study of transient surface charging during dielectric barrier discharges in air gap in needle-to-plane geometry
Authors: Yang Xin , Wang Wei , Wang Xinyan , Du Yan , Meng Yongpeng , Wu Kai
Published: August 2023

Motivated by a deeper understanding of plasma–surface interactions, this study presents experimental investigations into the transient surface charging process during dielectric barrier discharges (DBDs) in an air gap in a needle-to-plane geometry based on a combination of the Pockels method and a custom-designed ultrafast multi-frame imaging system. We realized three-frame observations of transient surface charge distributions, with a remarkable temporal resolution of 3 ns, during positive primary discharges and negative reverse discharges when applying a positive square-wave pulse. During the positive primary discharges at the rising voltage front, following the circular expansion of the streamer over the surface, multiple streamer filaments bifurcate simultaneously from the center, resulting in a branched positive surface charge distribution. Gradient surface charge densities are observed along the channel with higher charge densities at the head, which gradually evolve into a uniform distribution along the channel as the streamers approach stagnation. No lateral expansion of positive charges is observed across the channel under the present condition. In the case of negative reverse discharges occurring at the falling edge of the voltage pulse, the neutralization of residual positive surface charges and the accumulation of negative surface charges occur simultaneously in the central region. The deposited negative surface charges exhibit a progressively expanding circular distribution characterized by increasing charge density and radius. The propagation dynamics of surface streamers and the fields induced by surface charges are investigated and discussed based on the spatio-temporal surface charge measurements. Further study suggests that the surface streamer is not driven by the over-accumulation of surface charges, but rather by the space charge field above the dielectric. The presented quantitative measurements can be used for detailed validation of DBD simulations and offer deeper insights into plasma–surface interactions.
On the primary silicon precipitation during the eutectic solidification of Al–Si alloys
Authors: Majumder Anuruddha , Chatterjee Dipankar , Nandy Sambhunath
Published: August 2023

During the Al–Si eutectic alloy solidification, silicon distribution throughout the melt is not homogeneous which causes silicon segregation. A four phase Eulerian model of solidification is developed and invoked in Ansys Fluent simulation software to track the silicon segregation location and to understand the distribution of the segregating silicon in the Al–Si metal matrix. The recalescence phenomena are also observed during the solidification process. It is found that the silicon segregation is nearly 1.08 volume %, and the silicon is mostly found near the top surface of the simulation domain. It is also revealed through the numerical simulation that the columnar solid phase grains grow rapidly towards the center of the casting in the early stage of the solidification and the segregating silicon phase is generated near the columnar phase. However, the globular solid phases are also observed at the center of the simulation domain. The above numerical predictions are satisfactorily validated with the in-house experiment conducted using a specific alloy known as eutectic Al–Si (LM6).
Self-powered and broadband CuSCN/Si heterojunction photodetector for multi-color imaging based on diffuse reflection mode
Authors: Liu Yujin , Meng Yilong , Liu Junqing , Li Qingduan , Ji Zhong
Published: August 2023

Copper thiocyanate (CuSCN) has been widely used in photodetectors (PDs). However, the reported CuSCN-based PDs are suffered from narrow operating wavelength range and relatively low photodetection performance. Here, we fabricate an CuSCN/Si heterojunction PD by a simple low-temperature solution spin-coating method achieving excellent performance. Our designed CuSCN/Si PD exhibits a broadband response range covering ultraviolet–visible-infrared, a high detectivity of 2.26 × 1012 Jones coming from an ultralow dark current of 23 pA, and a decent responsivity of 11 mA W−1, a high linear dynamic range of 122 dB, and short response time of 25/150 μ (rise and decay time). Moreover, we demonstrate multi-color imaging across the wide wavelength range, indicating the CuSCN/Si PD has a promising potential in the imaging field. This work may pave the way for fabricating low-cost, nontoxicity, and high-performance CuSCN-based PD and broadening its applications.
On the structure of generic subshifts
Authors: Pavlov Ronnie , Schmieding Scott
Published: August 2023

We investigate generic properties (i.e. properties corresponding to residual sets) in the space of subshifts with the Hausdorff metric. Our results deal with four spaces: the space S of all subshifts, the space

S

′

of non-isolated subshifts, the closure

T

′

‾

of the infinite transitive subshifts, and the closure

T

T

′

‾

of the infinite totally transitive subshifts. In the first two settings, we prove that generic subshifts are fairly degenerate; for instance, all points in a generic subshift are biasymptotic to periodic orbits. In contrast, generic subshifts in the latter two spaces possess more interesting dynamical behavior. Notably, generic subshifts in both

T

′

‾

and

T

T

′

‾

are zero entropy, minimal, uniquely ergodic, and have word complexity which realizes any possible subexponential growth rate along a subsequence. In addition, a generic subshift in

T

′

‾

is a regular Toeplitz subshift which is strongly orbit equivalent to the universal odometer.
A lesson plan revisiting the Eratosthenes experiment to teach the seasons inductively from a space-based perspective
Authors: Aydin Mirac , Wiyarsi Antuni , Fitriyana Nur , Ilkbahar Mahmud Tugrul , Setiawan Ihsan Nur
Published: August 2023

This paper presents a lesson plan designed to teach seventh-grade students about the seasons and reflections of the students using an inductive approach from a space-based perspective. The plan establishes students’ prior knowledge of the topic and continues with the Eratosthenes experiment as a central experience. Eratosthenes experimented in the 250s BC and calculated the Earth’s circumference during the summer solstice in the Northern Hemisphere. Teachers used this experiment as a practical learning tool to teach the concept of seasons using the inductive method. Eleven seventh-grade students from Turkey, thirty middle-grade students from Indonesia, and their science teachers participated in the study. The students conducted the Eratosthenes experiment in vernal equinox in Turkey and Indonesia and calculated the circumference of the Earth. The measurements were taken in the experiment from a space-based perspective. After conducting the Eratosthenes experiment, the students reflected on their experiences. They discussed the connection of the experiment to the causes of the seasons. Afterwards, teachers conducted direct instruction and problem-solving activities related to the seasons. Reflections from student experiences and experiments were discussed. The study concluded that the lesson plan involving the Eratosthenes experiment provides an in-depth experience for students and enhances their understanding of the factors related to the space-based perspective.
Structural optimization of magnetostrictive composite materials in magnetostrictive current sensor
Authors: Xu Shaoyi , Sun Junwen , Wang Chengtao , Zhong Wenbing , Xing Fangfang
Published: August 2023

Fiber optic current sensor based on magnetostrictive composite material is suitable for multiple industrial fields. Aiming at increasing the low sensitivity caused by conventional magnetostrictive composites, this work designed optimized magnet focusing structure of magnetostrictive composite material to develop high-performance fiber optic current sensor. The influence of magnetic focusing structures on the performance of current sensor was analyzed and validated through theoretical modeling and finite element-based simulation. Experimental tests were carried out to validate the superiority of proposed sensor compared with the existing sensors. Results show that the dimensional difference in the four proposed magnetostrictive composite structures (section B) leads to the different magnetic field distribution, and the proposed sensors are more sensitive than those of traditional structures. A repeatability error of 2.5%, a sensitivity of 0.16952 μϵ A−1, and a linearity of 2.2% can be achieved by the proposed hourglass type sensor with low-cost and wide range between 0 A and 900 A.
Femtosecond pulse parameter estimation from photoelectron momenta using machine learning
Authors: Szołdra Tomasz , Ciappina Marcelo F , Werby Nicholas , Bucksbaum Philip H , Lewenstein Maciej , Zakrzewski Jakub , Maxwell Andrew S
Published: August 2023

Deep learning models have provided huge interpretation power for image-like data. Specifically, convolutional neural networks (CNNs) have demonstrated incredible acuity for tasks such as feature extraction or parameter estimation. Here we test CNNs on strong-field ionization photoelectron spectra, training on theoretical data sets to ‘invert’ experimental data. Pulse characterization is used as a ‘testing ground’, specifically we retrieve the laser intensity, where ‘traditional’ measurements typically lead to 20% uncertainty. We report on crucial data augmentation techniques required to successfully train on theoretical data and return consistent results from experiments, including accounting for detector saturation. The same procedure can be repeated to apply CNNs in a range of scenarios for strong-field ionization. Using a predictive uncertainty estimation, reliable laser intensity uncertainties of a few percent can be extracted, which are consistently lower than those given by traditional techniques. Using interpretability methods can reveal parts of the distribution that are most sensitive to laser intensity, which can be directly associated with holographic interferences. The CNNs employed provide an accurate and convenient ways to extract parameters, and represent a novel interpretational tool for strong-field ionization spectra.
Numerical and experimental study of the ultimate pressure and self-repairing capability of diverging magnetic fluid seal with stepped pole pieces
Authors: Cao Zhiqiang , Yang Xiaolong , Zhang Chengtao , Li Decai
Published: August 2023

With the objective of enhancing the performance of magnetic fluid seal in scenarios with large clearance, an innovative design of a diverging magnetic fluid seal with stepped pole piece has been developed. In contrast to the ordinary magnetic fluid seal, this new seal has advantages such as simple structure and high ultimate pressure. This study investigated the influence of different sealing gaps, step number and step height on both the ultimate pressure and self-repairing capability of the sealing device. The results indicate that the experimental and theoretical values of the new seals have similar trends, and their ultimate pressure and self-repairing capability are closely related to these parameters. These findings confirm the excellent sealing performance of the sealing device.
Generation of periodic evolution patterns by the interaction of pearcey-gaussian beams carrying sidelobe in parabolic potential
Authors: Wen Jianjun , Wang Haowen , Xiao Yan
Published: August 2023

Based on the fractional Schrödinger equation, the propagation properties of the Pearcey-Gaussian beam with the sidelobe in the parabolic potential are studied by using the split-step Fourier numerical simulation method. The focusing phenomenon appears without the parabolic potential when Pearcey-Gaussian beam carries the sidelobe. In the case of the parabolic potential, the beam forms the bound state in the propagation process. The period of the bound state decreases as the parabolic potential coefficient increases. In addition, the interaction of two Pearcey-Gaussian beams with the sidelobe in the potential is investigated. The effect of Lévy index, interval parameter, initial phase factor and parabolic potential coefficient on the interaction of two Pearcey-Gaussian beams with sidelobe is considered.
Casimir energy of N magnetodielectric δ-function plates
Authors: Abhignan Venkat
Published: August 2023

To investigate Casimir electromagnetic interaction in N bodies, we implement multiple δ-function plates with electric and magnetic properties. We use their optical properties to study the Casimir energy between the plates by implementing multiple scattering formalism. We initially solve Green’s functions for two and three plates configurations to obtain their reflection coefficients. Further, the coefficients are implemented in multiple scattering formalism, and a simple method was obtained to depict energy density distribution in the multiple scattering expansions using diagrammatic loops. The Casimir energy for N bodies depends on multiple scattering parameter Δ; this parameter was distributed into nearest neighbour scattering and next-to-nearest neighbour scattering terms represented by different loops depending on reflection, transmission and propagation distance. In this manner, the Casimir energy density was generalized to N plates by identifying a systematic pattern in the representation of diagrammatic loops.
The sojourn times of one dimensional discrete-time quantum walks
Authors: Cai Shuiying , Huang Qingyu , Ye Yiwen , Wen Yongxian , Lin Yunguo
Published: August 2023

In the existing literature, a sojourn time of a discrete-time quantum walk is not a random variable. To solve this problem, we redefine the sojourn time of a quantum walk where its coin evolution operator can be general. We first discuss a class of quantum walks governed by flip operators. We cumulatively calculate how much time a walker spends in the set of non-negative integers up to a fixed evolution time. Whether a walker makes a left or right evolution, we add up the staying times as long as it stays within the target set. We define a sojourn time as the total amount of the staying times. Compared with existing definitions, we show that this definition can satisfy the probability normalization. From this, we define a random variable about the sojourn time and discuss its probability distribution. We build a mathematical model to characterize a sojourn time that is embedded into a quantum walk. These results are also valid for a class of quantum walks governed by general coin operators. We also give a method for calculating the sojourn time and analyze the shape features of its probability distribution.
Non-SI units in the SI and their use with SI prefixes
Authors: Brown Richard J C
Published: August 2023

The International System of Units (SI) is one of the greatest scientific, technological, and political achievements of recent times. After the formal introduction of the SI, it was necessary to accept the ongoing usage of some non-SI units because of their long history of previous use, despite this losing the benefit of coherence that the SI brings. This work reviews the history of non-SI units that have been allowed for use with the SI in successive SI Brochures, observes the rules that have been required for this use especially with SI prefixes, and notes that this set of non-SI units has decreased significantly as the SI has become more deeply embedded in modern society. The current situation, where a relatively small set of non-SI units remain accepted for use with the SI, is analysed. It is observed that these non-SI units acquire quasi-SI status because of their listing in the SI Brochure. As a result, it is proposed that this set of non-SI units should be as small as possible and that clear rules for their use are necessary, most obviously with SI prefixes where the current guidance needs improvement. Historical precedent has been examined to assist in shaping these recommendations, which could be discussed and considered when the SI Brochure is next updated.
EEG-CDILNet: a lightweight and accurate CNN network using circular dilated convolution for motor imagery classification
Authors: Liang Tie , Yu Xionghui , Liu Xiaoguang , Wang Hongrui , Liu Xiuling , Dong Bin
Published: August 2023

Objective. The combination of the motor imagery (MI) electroencephalography (EEG) signals and deep learning-based methods is an effective way to improve MI classification accuracy. However, deep learning-based methods often need too many trainable parameters. As a result, the trade-off between the network decoding performance and computational cost has always been an important challenge in the MI classification research. Approach. In the present study, we proposed a new end-to-end convolutional neural network (CNN) model called the EEG-circular dilated convolution (CDIL) network, which takes into account both the lightweight model and the classification accuracy. Specifically, the depth-separable convolution was used to reduce the number of network parameters and extract the temporal and spatial features from the EEG signals. CDIL was used to extract the time-varying deep features that were generated in the previous stage. Finally, we combined the features extracted from the two stages and used the global average pooling to further reduce the number of parameters, in order to achieve an accurate MI classification. The performance of the proposed model was verified using three publicly available datasets. Main results. The proposed model achieved an average classification accuracy of 79.63% and 94.53% for the BCIIV2a and HGD four-classification task, respectively, and 87.82% for the BCIIV2b two-classification task. In particular, by comparing the number of parameters, computation and classification accuracy with other lightweight models, it was confirmed that the proposed model achieved a better balance between the decoding performance and computational cost. Furthermore, the structural feasibility of the proposed model was confirmed by ablation experiments and feature visualization. Significance. The results indicated that the proposed CNN model presented high classification accuracy with less computing resources, and can be applied in the MI classification research.
Transition Temperature of a Superconductor under a Helical Magnetic field
Authors: Kato Masaru
Published: August 2023

We consider a bilayer system with a conventional s-wave superconductor and a chiral helimagnet. If we assume that structure of an external magnetic field from the helimagnet is same as the magnetic moment structure in the helimagnet, a helical magnetic field is applied to the superconductor. Our previous simulation showed that vortex structures depend on strongly on structure of the helical magnetic field as well as the amplitude of the field. We study how pitch of the helical magnetic field affects the transition temperature. For this purpose, we formulate the linearized Ginzburg-Landau equation for the helical magnetic field.
Crystalline Orientation of CaF2 window determined by Neutron Transmission Imaging using a Delay Line Current-Biased Kinetic-Inductance Detector
Authors: Shishido Hiroaki , Dang Vu The , Aizawa Kazuya , Kojima Kenji M. , Koyama Tomio , Oikawa Kenichi , Harada Masahide , Oku Takayuki , Soyama Kazuhiko , Miyajima Shigeyuki , Hidaka Mutsuo , Suzuki Soh Y. , Tanaka Manobu M. , Kawamata Shuichi , Ishida Takekazu
Published: August 2023

The combination of a high speed two-dimensional neutron detector and an intensive pulsed neutron source provides not only neutron transmission imaging but also information on crystal structures, orientations and constituent elements by analyzing neutron transmission spectra. The delay-line current-biased kinetic-inductance detector (CB-KID) is a two-dimensional superconducting neutron detector with high spatial and temporal resolutions, and multi-hit tolerance. We demonstrated that the delay-line CB-KID with a 10B neutron conversion layer can be applied for neutron transmission measurements up to 100 keV. We observed two-different dip structures in the transmission spectra in a CaF2 single crystal, i.e., one is from the Bragg diffraction and the other is from nuclear resonance absorption. We consider that some duplicated structures in resonance absorption dips are originating from a double-bunch structure of proton pulses for producing pulsed neutrons in the accelerator.
Propagation in Superconducting Niobium Rectangular Waveguide in the 100 GHz band
Authors: Nakajima Taku , Suzuki Kazuji , Kojima Takafumi , Uzawa Yoshinori , Ishino Masayuki , Watanabe Issei
Published: August 2023

Rectangular waveguides that use superconducting materials for walls are expected to reduce transmission loss compared to normal metal waveguides. However, research on superconducting waveguides has been limited, particularly on the fabrication and measurement of physical models in the mm/sub-mm band. We attempted to fabricate a niobium (Nb) waveguide and measure its propagation. Because Nb is known to be a difficult-to-machine material, we searched for the best cutting tools and machining conditions. Consequently, we fabricated a waveguide with a surface accuracy of 0.3 µm rms using an end mill with a diameter of 1 mm. For the measurement of waveguide propagation, the resonator method was adopted, and the resonance characteristics were measured at room (298 K) and cryogenic (4.8 K) temperatures in the 100 GHz band. The resonance property at 298 K is consistent with the shapes predicted from literature-based conductivity. However, at 4.8 K, that of superconducting Nb is significantly changed. We used electromagnetic analysis to reproduce these properties, and the electrical conductivity and propagation loss were calculated. The conductivity and loss were computed as 1.8×1011 S/m and 0.05 dB/m, respectively. We observed a slight transmission loss and verified the effectiveness of the superconducting waveguides.
Air-to-land transitions: from wingless animals and plant seeds to shuttlecocks and bio-inspired robots
Authors: Ortega-Jimenez Victor M , Jusufi Ardian , Brown Christian E , Zeng Yu , Kumar Sunny , Siddall Robert , Kim Baekgyeom , Challita Elio J , Pavlik Zoe , Priess Meredith , Umhofer Thomas , Koh Je-Sung , Socha John J , Dudley Robert , Bhamla M Saad
Published: August 2023

Recent observations of wingless animals, including jumping nematodes, springtails, insects, and wingless vertebrates like geckos, snakes, and salamanders, have shown that their adaptations and body morphing are essential for rapid self-righting and controlled landing. These skills can reduce the risk of physical damage during collision, minimize recoil during landing, and allow for a quick escape response to minimize predation risk. The size, mass distribution, and speed of an animal determine its self-righting method, with larger animals depending on the conservation of angular momentum and smaller animals primarily using aerodynamic forces. Many animals falling through the air, from nematodes to salamanders, adopt a skydiving posture while descending. Similarly, plant seeds such as dandelions and samaras are able to turn upright in mid-air using aerodynamic forces and produce high decelerations. These aerial capabilities allow for a wide dispersal range, low-impact collisions, and effective landing and settling. Recently, small robots that can right themselves for controlled landings have been designed based on principles of aerial maneuvering in animals. Further research into the effects of unsteady flows on self-righting and landing in small arthropods, particularly those exhibiting explosive catapulting, could reveal how morphological features, flow dynamics, and physical mechanisms contribute to effective mid-air control. More broadly, studying apterygote (wingless insects) landing could also provide insight into the origin of insect flight. These research efforts have the potential to lead to the bio-inspired design of aerial micro-vehicles, sports projectiles, parachutes, and impulsive robots that can land upright in unsteady flow conditions.
Fabrication and application of graphene-based silicone grease
Authors: Thi Mai Phuong , Nguyen Nghia Phan Trong , Nguyen Tuyen Viet , Minh Phan Ngoc , Thi Vu Thu Ha , Thi Au Hang , Bui Thang Hung
Published: August 2023

With the increasing power requirements of integrated circuits, the demand for efficient cooling has followed suit. Silicone grease is commonly used due to its thermal stability and ability to fill in airgaps between the electronic components and radiators. Previous works attempted to increase the grease’s thermal conductivity by adding various additives such as boron nitride or functionalized carbon nanotubes. Functionalized graphene was chosen in this study due to its exceptional physical and chemical properties. Results show that the functionalization with several acid mixtures combined with ball milling resulted in a compound chemically equivalent to graphene and thoroughly dispersed in silicone grease. An optimal grease was produced, containing 1 wt% Gr-COOH and possessing a thermal conductivity of 6.534 W mK−1. The resulting grease’s performance in thermal dissipation and approximated lifespan improvements was compared to a commercially available silicone grease using a 200 W LED. Results indicated a 4.5 °C decrease in saturation temperature of LED chip along with a 257% increase in thermal conductivity.
Compliance-Adjusted Estimates of Aspirin Effects Among Older Persons in the ASPREE Randomized Trial
Authors: Smith C L , Kasza J , Woods R L , Lockery J E , Kirpach B , Reid C M , Storey E , Nelson M R , Shah R C , Orchard S G , Ernst M E , Tonkin A M , Murray A M , McNeil J J , Wolfe R
Published: August 2023

The Aspirin in Reducing Events in the Elderly (ASPREE) Trial recruited 19,114 participants across Australia and the United States during 2010–2014. Participants were randomized to receive either 100 mg of aspirin daily or matching placebo, with disability-free survival as the primary outcome. During a median 4.7 years of follow-up, 37% of participants in the aspirin group permanently ceased taking their study medication and 10% commenced open-label aspirin use. In the placebo group, 35% and 11% ceased using study medication and commenced open-label aspirin use, respectively. In order to estimate compliance-adjusted effects of aspirin, we applied rank-preserving structural failure time models. The results for disability-free survival and most secondary endpoints were similar in intention-to-treat and compliance-adjusted analyses. For major hemorrhage, cancer mortality, and all-cause mortality, compliance-adjusted effects of aspirin indicated greater risks than were seen in intention-to-treat analyses. These findings were robust in a range of sensitivity analyses. In accordance with the original trial analyses, compliance-adjusted results showed an absence of benefit with aspirin for primary prevention in older people, along with an elevated risk of clinically significant bleeding.
Limping Marriages: Race, Class, and the Rise of Domicile-Based Divorce Jurisdiction in the British Empire
Authors: Saksena Priyasha
Published: August 2023

In this article, I trace the development of domicile as the basis of divorce jurisdiction in English private international law. The maintenance of English domicile became closely related to the retention of ‘white’ identity, with white British subjects who became domiciled in non-white colonies such as India being relegated to racially ambiguous statuses. The domicile rule limited the remedy of divorce to those who were financially well-off and able to travel to the courts of the metropole since English courts refused to recognize divorce decrees granted by British Indian courts based on residence. As a result, innumerable British subjects who obtained a divorce in India remained married in Britain, i.e. were stuck in so-called ‘limping marriages’. To remedy this situation, a separate divorce regime was enacted for British subjects residing in India but domiciled in England and Scotland, but it replicated the class barriers of the original domicile rule. Law, therefore, played a significant role in the creation of the mutually constitutive but unstable categories of class and race.