bluuebunny/crossref_metadata_2025 huggingface dataset:
Unexpected thermal transport properties of MgSiO3 monolayer at extreme conditions
Authors: Zuo Jingning , Bi Jie , He Shi , Jin Wenyuan , Yu Xin , He Kaihua , Dai Wei , Lu Cheng
Published: April 2024

The thermal transport properties of mantle minerals are of paramount importance to understand the thermal evolution processes of the Earth. Here, we perform extensively structural searches of two-dimensional MgSiO3 monolayer by CALYPSO method and first-principles calculations. A stable MgSiO3 monolayer with Pmm2 symmetry is uncovered, which possesses a wide indirect band gap of 4.39 eV. The calculations indicate the lattice thermal conductivities of MgSiO3 monolayer are 49.86 W (mK)−1 and 9.09 W (mK)−1 in x and y directions at room temperature. Our findings suggest that MgSiO3 monolayer is an excellent low-dimensional thermoelectric material with high ZT value of 4.58 from n-type doping in the y direction at 2000 K. The unexpected anisotropic thermal transport of MgSiO3 monolayer is due to the puckered crystal structure and the asymmetric phonon dispersion as well as the distinct electron states around the Fermi level. These results offer a detailed description of structural and thermal transport properties of MgSiO3 monolayer at extreme conditions.
Quantum critical fluctuations in a transverse-field Ising magnet
Authors: Hauspurg A , Matsuura K , Arima Taka-hisa , Zherlitsyn S , Wosnitza J
Published: April 2024

CoNb2O6 is a model system for a spin-1/2 one-dimensional (1D) transverse-field Ising magnet (TFIM) with a rather low three-dimensional (3D) Néel ordering temperature at

T
N

=
2.95

K. We studied CoNb2O6 using ultrasound measurements down to 0.3 K in transverse magnetic fields applied along the b direction. Upon entering the 3D ordered state, we observe pronounced anomalies in the transverse acoustic mode c
66. In particular, from 1.3 to 1.5 K and around 4.7 T, this mode reveals an almost diverging softening, which is considerably reduced at lower and higher magnetic fields. We interpret this as an influence of quantum critical fluctuations emerging from the quantum critical point (QCP) of the 1D Ising spin chains at about 4.75 T, which lies below the QCP of the 3D ordering at about 5.4 T. This is clear experimental evidence of the predicted generic phase diagram for a TFIM with superimposed 3D ordering.
Insights into the writing process of the mask-free nanoprinting fluid force microscopy technology
Authors: Soter Marcus , Apte Gurunath , Madkatte Dikshita , Nguyen Thi-Huong
Published: April 2024

Platelets are activated immediately when contacting with non-physiological surfaces. Minimization of surface-induced platelet activation is important not only for platelet storage but also for other blood-contacting devices and implants. Chemical surface modification tunes the response of cells to contacting surfaces, but it requires a long process involving many regulatory challenges to transfer into a marketable product. Biophysical modification overcomes these limitations by modifying only the surface topography of already approved materials. The available large and random structures on platelet storage bags do not cause a significant impact on platelets because of their smallest size (only 1–3 μm) compared to other cells. We have recently demonstrated the feasibility of the mask-free nanoprint fluid force microscope (FluidFM) technology for writing dot-grid and hexanol structures. Here, we demonstrated that the technique allows the fabrication of nanostructures of varying features including grid, circle, triangle, and Pacman-like structures. Characteristics of nanostructures including height, width, and cross-line were analyzed and compared using atomic force microscopy imaging. Based on the results, we identified several technical issues, such as the printing direction and shape of structures that directly altered nanofeatures during printing. Importantly, both geometry and interspace governed the degree of platelet adhesion, especially, the structures with triangular shapes and small interspaces prevent platelet adhesion better than others. We confirmed that FluidFM is a powerful technique to precisely fabricate a variety of desired nanostructures for the development of platelet/blood-contacting devices if technical issues during printing are well controlled.
Research on load monitoring technology of mine hoist based on machine vision
Authors: Tian Zuzhi , Wang Zezheng , Guo Yangyang , Chen Huijun , Zhu Minjian
Published: April 2024

A hoist load monitoring method based on machine vision technology is proposed in this paper to address the frequent overloading accidents of mine hoists and the low safety and reliability of existing contact load monitoring technologies. The depth image of the skip undergoes time domain and spatial bilateral filtering algorithms for noise reduction, followed by conditional filtering and downsampling algorithms to remove redundant point cloud data. Point cloud recognition, extraction, segmentation, and alignment algorithms are then applied to quickly generate a skip point cloud model. A surface reconstruction optimization process combining greedy projection triangulation algorithm and void repair algorithm is proposed to obtain a smooth and complete sealing of the skip. The closed surface model volume is calculated using VTK volume function. Based on single-rope winding hoist, a load visual monitoring system is constructed for relevant experimental research. Results show that this method can accurately measure the loaded coal volume with a relative error range of 0.05%–4.13%, meeting practical application requirements while providing an effective way for non-contact accurate measurement of hoist loads in mines.
Three 1-bit speckle-embedded pulse-width modulation patterns for robust absolute 3D measurement
Authors: Zheng Yanjun , Li Xiao , Zuo Chenglin , Gao Zhisheng
Published: April 2024

In three-dimensional (3D) shape measurement techniques using structured light, 1-bit pulse-width modulation (PWM) patterns and 1-bit speckle patterns can be projected at high speed. However, when combining PWM and speckle patterns to integrate their advantages, the decoupling problem is insurmountable. In this work, a novel 1-bit speckle-embedded PWM (SPPWM) method was proposed to achieve absolute 3D shape measurement using only three binary patterns. Our method consists of three main steps: First, a sinusoidal pattern reconstruction network was proposed to eliminate the high-order harmonics and speckle patterns in the SPPWM patterns and obtain high-quality sinusoidal patterns. Second, a multi-temporal spatial correlation matching algorithm was proposed to obtain a coarse disparity map from the three SPPWM patterns. Third, the high-accuracy wrapped phase map is used as an additional constraint for refining the coarse disparity map to obtain the final high-accuracy disparity map for absolute 3D measurement without phase unwrapping. Our method combines the advantages of fringe projection profilometry techniques for high-precision wrapped phase retrieval and speckle correlation matching algorithms for robust and unambiguous disparity map calculation. The experimental results demonstrated that our method could realize high-precision absolute 3D shape measurement with an accuracy of 0.057 mm using only three 1-bit SPPWM patterns. Furthermore, different simulation noises were used to demonstrate the robustness of the proposed method.
Method for measuring non-stationary motion attitude based on MEMS-IMU array data fusion and adaptive filtering
Authors: Lan Jianping , Wang Kaixuan , Song Sujing , Li Kunpeng , Liu Cheng , He Xiaowei , Hou Yuqing , Tang Sheng
Published: April 2024

The error characteristics of a typical commercial MEMS-IMU were analyzed. Using 15 ICM-42688 sensors, a 3*5 MEMS-IMU array was designed, and a weighted data fusion method based on Allan variance for the MEMS-IMU array was proposed. This effectively reduces the random measurement errors of the MEMS-IMU, providing a data foundation for the precise measurement of motion and attitude of robots, vehicles, aircraft, and other systems under low-cost conditions. The text describes a measurement method for non-stationary motion attitudes of sports vehicles based on adaptive Kalman-Mahony. Specifically, it first uses adaptive Kalman filter on array sensor data to calculate the measurement noise in real-time and adaptively adjust the filtering gain. Then, it determines the compensation coefficient of the accelerometer to the gyroscope angular velocity based on the motion state of the vehicle, and solves the attitude through complementary filtering to obtain the motion attitude quaternion. Finally, it converts it into the roll angle, pitch angle, and yaw angle of the sports vehicle. Experimental results show that the proposed MEMS-IMU array weighted data fusion method based on Allan variance has significant advantages over traditional single MEMS-IUM methods and traditional average weighting methods in reducing sensor angle random walk and zero drift instability. The proposed adaptive Kalman-Mahony attitude measurement method also shows a significant improvement in the accuracy of non-stationary motion attitude measurement compared to traditional methods.
A falls recognition framework based on faster R-CNN and temporal action sequences that can be deployed on home service robots
Authors: Mei Songzhu , Liu Cong , Lv Xuefeng
Published: April 2024

With the popularity of home service robots (e.g. floor sweepers), robots should be considered to have more features for older adult care. Compared to fixed home monitors with a limited field of view, fall detection with service robots is an ideal solution to keep older adults and disabled people within sight. However, the user’s actions, such as lying on the bed to sleep or slumping on the sofa to rest, cause the traditional fall detection system to generate false alarms, which disrupts the user’s family life. The present work proposed an enhanced faster R-convolutional neural network (CNN) network by incorporating temporal action sequences and fall acceleration computation, demonstrating a reduced misjudgment rate on the service robot platform. Firstly, motion images were captured to obtain the target’s motion area description and action timing at the input stage. Then, the faster R-CNN algorithm was implemented to check the suspected falls further based on the falling acceleration of the detected actions during the training phase. Finally, the proposed temporal action sequences module eliminated the action mistaken for falling. Network training and robotic platform testing demonstrated that the proposed approach distinguished between falls and false alarms, which mitigated the occurrence of false positives. On the service robot platform, experimental results showed that the FAR was 8.19 and processing time was 0.79 s.
Direct integration of measured viscoelastic relaxation data in time-domain finite element simulations
Authors: Abercrombie Eric , McDaniel J Gregory
Published: April 2024

The current approach to modeling viscoelastic materials in most commercial finite element packages is based on the General Maxwell Model, which views these materials as combinations of spring and dashpot elements. However, the data can be incorporated more directly into a transient finite element study by direct interpolation of the relaxation function. This work explores a linear interpolation scheme to the inclusion of viscoelastic relaxation functions on an example problem. The results show several benefits over the General Maxwell Model for transient studies. Included in the analysis are displacement solutions utilizing both approaches, relaxation function error calculations for both approaches, and parametric runtime studies comparing speed of calculation. The variation in computational flop counts is considered and an argument is made for the preference of the proposed approach.
Microscopic insights into metal diffusion and ohmic contact formation in delta-doped GaAs/(Al,Ga)As core/shell nanowires
Authors: Ayuso-Pérez Irene , Luna Esperanza , da Silva Alessandra , Ruhstorfer Daniel , Matzeck Margarita , Koblmüller Gregor , Engel-Herbert Roman
Published: April 2024

Semiconductor nanowires (NWs) are promising candidates for use in electronic and optoelectronic applications, offering numerous advantages over their thin film counterparts. Their performance relies heavily on the quality of the contacts to the NW, which should exhibit ohmic behavior with low resistance and should be formed in a reproducible manner. In the case of heterostructure NWs for high-mobility applications that host a two-dimensional electron gas, ohmic contacts are particularly challenging to implement since the NW core constituting the conduction channel is away from the NW surface. We investigated contact formation to modulation-doped GaAs/(Al,Ga)As core/shell NWs using scanning transmission electron microscopy, energy dispersive x-ray spectroscopy and electron tomography to correlate microstructure, diffusion profile and chemical composition of the NW contact region with the current–voltage (I–V) characteristics of the contacted NWs. Our results illustrate how diffusion, alloying and phase formation processes essential to the effective formation of ohmic contacts are more intricate than in planar layers, leading to reproducibility challenges even when the processing conditions are the same. We demonstrate that the NW geometry plays a crucial role in the creation of good contacts. Both ohmic and rectifying contacts were obtained under nominally identical processing conditions. Furthermore, the presence of Ge in the NW core, in the absence of Au and Ni, was found as the key factor leading to ohmic contacts. The analysis contributes to the current understanding of ohmic contact formation to heterostructure core/shell NWs offering pathways to enhance the reproducibility and further optimization of such NW contacts.
Rapid low-temperature densification of Ag2Se bulk material: mass transfer through the dissociative adsorption reaction of Ag protrusions and Se saturated vapor
Authors: Zheng Yu , Yang Dongwang , Zhang Mingqi , Jia Yongzhong , Li Junhao , Gou Weijie , Wang Yuting , Melzi Bachir , Yan Yonggao , Tang Xinfeng
Published: April 2024

In materials science, the impact of density on a material’s capabilities is profound. Conventional sintering requires high temperatures and is energy-demanding, propelling the pursuit of less intensive, low-temperature densification methods. Electric field-assisted sintering has recently gained attention for its simplicity and effectiveness, offering a new frontier in low-temperature densification. In this study, dense bulk materials were produced by subjecting monophasic Ag2Se powders to electric field-assisted sintering, where a direct current with an average value of 4 A was applied, achieving a peak temperature of 344 K. The novel low-temperature densification mechanism unfolds thus: nanoscale silver protrusions, stimulated by electrical current, engage in a dissociative adsorption reaction with the ambient saturated selenium vapor. This process swiftly engenders the formation of fresh silver selenide (Ag2Se) compounds, initiating nucleation and subsequent growth. Consecutively, these compounds seamlessly occupy and expand, perpetually bridging the interstices amidst the powders. In a scant 8 s, the density swiftly surpassed 99%, yielding a bulk material that exhibited a ZT value of 1.07 at 390 K. This investigation not only attains an unparalleled density at low temperatures but also charts a pioneering course for material densification in such conditions.
Global existence and blowup of solutions to a class of wave equations with Hartree type nonlinearity
Authors: Zhang Hongwei , Su Xiao , Liu Shuo
Published: April 2024

In this paper, we consider a class of wave-Hartree equations on a bounded smooth convex domain with Dirichlet boundary condition. We prove the local existence of solutions in the natural energy space by using the standard Galërkin method. The results on global existence and nonexistence of solutions are obtained mainly by means of the potential well theory and concavity method.
Active and passive dosimetry for beta-emitting radiopharmaceutical therapy agents in a custom SPECT/CT compatible phantom
Authors: Bertinetti Andrew , Garcia Timothy , Palmer Benjamin , Rodrigues Miesher , Bradshaw Tyler , Vija A Hans , Culberson Wesley
Published: April 2024

Objective. This work introduces a novel approach to performing active and passive dosimetry for beta-emitting radionuclides in solution using common dosimeters. The measurements are compared to absorbed dose to water (D
w) estimates from Monte Carlo (MC) simulations. We present a method for obtaining absorbed dose to water, measured with dosimeters, from beta-emitting radiopharmaceutical agents using a custom SPECT/CT compatible phantom for validation of Monte Carlo based absorbed dose to water estimates. Approach. A cylindrical, acrylic SPECT/CT compatible phantom capable of housing an IBA EFD diode, Exradin A20-375 parallel plate ion chamber, unlaminated EBT3 film, and thin TLD100 microcubes was constructed for the purpose of measuring absorbed dose to water from solutions of common beta-emitting radiopharmaceutical therapy agents. The phantom is equipped with removable detector inserts that allow for multiple configurations and is designed to be used for validation of image-based absorbed dose estimates with detector measurements. Two experiments with 131I and one experiment with 177Lu were conducted over extended measurement intervals with starting activities of approximately 150–350 MBq. Measurement data was compared to Monte Carlo simulations using the egs_chamber user code in EGSnrc 2019. Main results. Agreement within k = 1 uncertainty between measured and MC predicted D
w was observed for all dosimeters, except the A20-375 ion chamber during the second 131I experiment. Despite the agreement, the measured values were generally lower than predicted values by 5%–15%. The uncertainties at k = 1 remain large (5%–30% depending on the dosimeter) relative to other forms of radiation therapy. Significance. Despite high uncertainties, the overall agreement between measured and simulated absorbed doses is promising for the use of dosimeter-based RPT measurements in the validation of MC predicted D
w.
Tomographic reconstructions of the fast-ion phase space using imaging neutral particle analyser measurements
Authors: Rueda-Rueda J , Garcia-Munoz M , Viezzer E , Schneider P A , Oyola P , Galdon-Quiroga J , Salewski M , Schmidt B S , Garcia-Dominguez J ,   ASDEX Upgrade team
Published: April 2024

In this paper we demonstrate how the inversion, in energy and major radius (E, R) coordinates, of imaging neutral particle analyser (INPA) measurements can be used to obtain the fast-ion distribution. The INPA is most sensitive to passing ions with energies in the range (20–150) keV and pitches near 0.5 in the core and 0.7 near the plasma edge. Inversion of synthetic signals, via 0th-order Tikhonov and Elastic Net regularization, were performed to demonstrate the capability of recovering the ground truth fast-ion 2D phase-space distribution resolved in major radius and energy, even in the presence of moderate noise levels (10%). Finally, we apply our method to measure the 2D phase-space distribution in an MHD quiescent plasma at ASDEX Upgrade and find good agreement with the slowing down fast-ion distribution predicted by TRANSP.
Optimization of the
N∥
Upshift in the DIII-D high field side lower hybrid current drive experiment
Authors: Rutherford Grant , Frank Samuel J , Seltzman Andrew H , Bonoli Paul T , Wukitch Stephen J
Published: April 2024

High field side lower hybrid current drive (LHCD) is one potential candidate for efficient non-inductive current drive in tokamak power plants, and the first test of this technology will occur on the DIII-D tokamak during the 2024 campaign. Previous LFS launch experiments operated in the multi-pass regime and relied on scrape-off layer interactions to close the spectral gap. In the DIII-D experiment, single-pass damping is achievable via an upshift in the parallel refractive index

N
∥

caused by mode converting twice (slow

→

fast

→

slow). This mode conversion affects the ray trajectories and can lead to enhanced

N
∥

upshift depending on where mode conversion occurs. Compared to multi-pass absorption experiments, the optimization of launched

N
∥

and plasma parameters can be counter-intuitive: increased density may increase efficiency and smaller

N

∥
,

launch

tend to damp closer to the separatrix. A hard x-ray camera installed to measure the bremsstrahlung (50–250 keV) radiation from LHCD-generated fast electrons is capable of verifying the trends reporting in this paper through comparison to the ray-tracing/Fokker–Planck codes GENRAY/CQL3D.
23 Tesla high temperature superconducting pocket magnet
Authors: Gao Chukun , Chen Pin-Hui , Alaniva Nicholas , Björgvinsdóttir Snædís , Pagonakis Ioannis , Däpp Alexander , Urban Michael , Gunzenhauser Ronny , Barnes Alexander
Published: April 2024

We present a compact 23 T no-insulation (NI) magnet that was wound with 60 m of 10 mm wide high temperature superconducting (HTS) tape. The magnet consists of only one pocket-sized double pancake (DP) coil with an inner diameter of ∼6 mm, a height of 20 mm, and an outer diameter of 41.6 mm. Another NI coil of similar size but with a larger inner diameter of 8 mm reached a slightly lower magnetic field of 21 T. We also present a smaller coil which was wound with only 20 m of HTS tape and still achieved a magnetic field of 16 T. During the experiments in liquid helium, each coil was charged to a current between 690 A and 850 A, corresponding to a high current density of 1500–1900 A mm−2. The small bore size and high current density contributed to the high fields generated by these coils. We present the fabrication details, helium tests and repeatability analysis of these ‘pocket’ magnets.
Experimental study on screening-current induced strain in REBCO insert coils: under critical current control and operation current cycles
Authors: Shao Liangjun , Zhang Yongjie , Xin Canjie , Liu Fang , Yan Yufan , Li Yi , Yue Yubin , Xu Ziyang , Song Peng , Zhang Xintao , Liu Huajun , Guan Mingzhi , Qu Timing
Published: April 2024

The screening-current effect is an inhomogeneous distribution of current density inside the REBCO conductors. The additional strain induced by the screening current, known as screening-current induced strain (SCS), is considered to affect the structural integrity of REBCO windings, especially when operating high-field REBCO insert magnets. In this work, we wound and tested a series of 50-turn REBCO coils inside a 10 T LTS external to investigate the influencing mechanism of multiple electromagnetic factors on SCS. We varied the critical current in different coils by different heat treatment procedures. Each coil was tested individually, experiencing a external field cycle and multiple operation current cycles at constant external fields. The extreme scenario for each coil was being energized to 400 A while the external field was 10 T. We adapted the discrete-coupled model to estimate the hoop strain distribution, monitored the experimental results by multiple strain gauges at the outermost turn. Test coil with a lower critical current endured a lower maximum hoop strain. When we were energizing the test coils, hoop strain increased at the edge of REBCO tapes while remaining nearly constant in the middle region. Additionally, the maximum hoop strain at the outermost turn decreased after each excitation cycle. This work could be an experimental reference for optimizing the electromagnetic design and the excitation scheme during the development of high-field REBCO magnets.
Theoretical proposal for a broadband on-chip multistage quantum amplifier
Authors: Huang Rutian , Shi Yunfan , Liu Jianshe , Chen Wei
Published: April 2024

A broadband on-chip multistage quantum amplifier (MQA) for reading out multiple superconducting qubits is proposed. The bandwidth of quantum amplifier is enhanced by concatenating amplifiers with modular nonreciprocal elements, which are superconducting isolators and circulators based on tunable inductor bridge. The circuit model of MQA is built and simulated. The variation of bandwidth, gain and gain-bandwidth product (GBP) of MQA with the number of stages and bandpass of the constitutive amplifiers are simulated. It is revealed that the bandwidth can be as large as ∼3.2 GHz with a gain of 20 dB at 4–8 GHz frequency range. For a 4-stage MQA composed of four quantum amplifiers with 20 dB gain and 0.3 GHz BW-pass, the bandwidth is 2.14 GHz at 20 dB gain, which is quite cost-efficient. Due to its non-reciprocity, MQA can effectively prevent signals from reflecting to quantum processors. In addition, MQA breaks the limitation of GBP and is easy to integrate with superconducting circuits. The MQA would play a crucial role in the high-fidelity readout of multiple qubits in large-scale superconducting quantum computers.
A binary neural computing unit with programmable gate using SFQ and CMOS hybrid circuit
Authors: Li Zongyuan , Shen Hongxiang , Yoshikawa Nobuyuki , Yamanashi Yuki
Published: April 2024

Superconducting neural networks hold significant potential for future applications such as natural language processing and image recognition. To this end, we propose a binary neural computing unit implemented using a hybrid circuit of cryogenic CMOS and superconducting technologies. It offers two main advantages: firstly, we utilize current-mode computations for neural unit weight calculations, significantly reducing the unit’s footprint and enabling the potential for higher integration in the future. Secondly, all computations are performed in a low-temperature environment, which implies the possibility of on-chip learning in superconducting neural networks and the potential for achieving faster training rates in the future. We fabricated the chip using Nb 1 kA cm−2 process (1KP) technology and experimentally verified the correctness of the circuit logic. The margins for various control parameters of the circuit are approximately around 30%, and the superconducting circuit power consumption is estimated to be around 4 microwatts.
Hybrid synaptic structure for spiking neural network realization
Authors: Razmkhah S , Karamuftuoglu M A , Bozbey A
Published: April 2024

Neural networks and neuromorphic computing represent fundamental paradigms as alternative approaches to Von-Neumann-based implementations, advancing in the applications of deep learning and machine vision. Nonetheless, conventional semiconductor circuits encounter challenges in achieving ultra-fast processing speed and low power consumption due to their dissipative properties. Conversely, single flux quantum circuits exhibit inherent spiking behavior, showcasing their characteristics as a promising candidate for spiking neural networks (SNNs). In this work, we present a compact hybrid synapse circuit to mimic the biological interconnect functionality, enabling the weighting operations for excitatory and inhibitory impulses. Additionally, the proposed structure facilitates input accumulation, which is performed before the activation function. In the experiments, our synaptic structure interfaces with a soma circuit fabricated using a commercial Nb process, underscoring its compatibility and supporting its potential for integration into efficient neural network architectures. The weight value on the synapse is configurable by utilizing cryo-CMOS circuits, providing adaptability to the inference networks. We’ve successfully designed, fabricated, and partially tested the JJ-Synapse within our cryocooler system, enabling high-speed inference implementation for SNNs.
A newly developed 10 kA-level HTS conductor: innovative tenon-mortise-based modularized conductor (TMMC) based on China ancient architecture
Authors: Zheng Jinxing , Cheng Yuan , Wang Lei , Liu Fei , Liu Haiyang , Li Ming , Zhu Lei
Published: April 2024

We proposed a new type of high-temperature superconducting (HTS) conductor concept: modularized conductors (MCs) connected by Chinese traditional tenon-mortise (TM) connection structure, referred as TMMC (tenon-mortise modularized conductor). The conductor consisted of multiple concentric round sub-conductors with slots for stacking rare-earth-barium-copper-oxide (REBCO) tapes. Innovatively, the REBCO stacks in the adjacent sub-conductors were arranged with the fully-misaligned configuration to enhance the critical current’s isotropy with respect to magnetic field and reduce ac loss. For example, the angle between the adjacent stacks in the two adjacent sub-conductors was 45° if each sub-conductor contains 4 REBCO stacks. In order to construct the fully-misaligned configuration, the sub-conductors were designed with two open half-circular formers and connected by TM structure which makes the conductor modularized and simply to assembly and disassembly. Based on the design concept, a prototype conductor containing 160 REBCO tapes distributed in the four concentric sub-conductors was fabricated. The conductor’s measured critical current was 13.69 kA at 77 K and self-field, which was consistent to the simulation result. In order to further improve the TMMC’s engineering critical current density (J
ce) and bending performance, we proposed two enhancement approaches: reducing the former’s thickness and re-arrange stacks in the outer sub-conductors. With the enhancements, both TMMC’s radius and J
ce were comparable to the existing slotted-core conductor. The study shows the TMMC’s advantages of non-twisted structures, easy assembly, high-current carrying and low ac losses, which made it promising for constructing large-scale scientific devices.
Theoretical characterization and its application of electromagnetic anisotropy in high-temperature superconducting bulks under rotated postures
Authors: Cheng Yanxing , Wang Li , Huang Huan , Liu Xiaoning , Zheng Jun
Published: April 2024

The electromagnetic anisotropy of high-temperature superconducting (HTS) bulks limits their levitation ability in the applied magnetic fields from the permanent magnet guideway (PMG), thus impeding the enhancement of load-carrying capacity in HTS pinning maglev systems. Developing a suitable matching scheme between bulk orientation and magnetic field direction is a valuable way to relieve this restriction. In this paper, a method for characterizing bulk anisotropy in a rotating coordinate system is proposed to explore the best bulk orientation. The method is based on the concept of equivalent resistivity tensor and its eigenvectors, and includes an extended description of two types of anisotropy: conductivity anisotropy and magnetic field angle dependence. It provides a theoretical foundation for simulating anisotropic bulks under any rotated posture. Experimental investigations on the levitation force distribution of cylindrical bulks with different c-axis orientation were conducted, through which the accuracy of the characterization method and calculated results were validated. Analysis of current distribution reveals that aligning the c-axis parallel to the external magnetic field helps achieve the best match between the bulk and the PMG. Additionally, considering that the two types of anisotropy have opposite effects on levitation force distribution trends, prioritizing conductivity anisotropy when analyzing anisotropic bulk is recommended. This research not only offers a theoretical framework for simulating the anisotropy of rotated HTS bulks but also provides guidance for matching the optimal bulk orientation in applied magnetic fields.
Superluminal propagation of surface plasmon polaritons via hybrid chiral quantum dots system
Authors: Idrees Muhammad , Li Hui-Jun
Published: April 2024

We present a novel methodology for enhancing superluminal surface plasmon polaritons (SPPs) propagations within a hybrid nanostructure configuration consisting of gold (Au) metal and chiral quantum dots (CQDs) medium. The arrangement of CQDs and metal hybrid nanostructures enables the production of SPPs when exposed to incident light. The resonances of SPPs within a hybrid nanostructure are determined through analytical calculations using Maxwell’s equations under specified boundary conditions, while the dynamics of the CQDs system are calculated using the density matrix approach. It is demonstrated that the propagation of SPPs is significantly influenced by both right-circularly polarized (RCP) and left-circularly polarized (LCP) SPPs. Additionally, we investigate the enhancement of superluminal SPPs propagation by varying the electron tunneling strength and the intensity of the control field within the hybrid system. The characteristics of RCP and LCP SPPs have been investigated, indicating a large negative group index and advancement in time. The observation of a large negative group index and advancement in time provides strong evidence for enhanced superluminal SPPs propagation within the proposed hybrid nanostructure. The results have potential applications in the fields of optical information processing, temporal cloaking, quantum communication, and the advancement of computer chip speed.
Bulk α-alumina embedded tapered fiber as Q-switcher in an erbium-doped fiber laser
Authors: Yusoff Norita Mohd , Chyi Josephine Liew Ying , Ng Eng Khoon , Zain Ahmad Rifqi Md , Alresheedi Mohammed Thamer , Mayzan Mohd Zul Hilmi , Mahdi Mohd Adzir
Published: April 2024

We present bulk α-alumina (Al2O3) in a polydimethylsiloxane matrix decorated tapered fiber as a Q-switcher for microsecond pulse generation. The integration of α-Al2O3-saturable absorber (SA) in an erbium-doped fiber laser yielded a Q-switched operating regime within 62.0–308.6 mW pump power. The shortest pulse width was 7 μs, whereas the repetition rate was tunable from 19.17 to 43.24 kHz. This work reveals a substantial improvement over previously reported Al2O3-SA works with a recorded pulse energy of 150.32 nJ and an estimated damage threshold of beyond 6.75 GW cm−2 incident intensity. Our findings suggest that α-Al2O3-SA has enormous potential as a next generation light-absorbing material for high-energy photonic devices.
Anodic oxidation- and hydrogenation-produced TiO2 nanotubes on titanium and its effect on gingival epithelial cell adhesion ability
Authors: Mu Yanting , Wang Xin , Lu Ran , Wang Caiyun , Cao Xu , Li Bing , Chen Su , Zhou Jian
Published: April 2024

The gingival epithelium plays a crucial role in achieving long-term stability of dental implants, and the hydrogenated TiO2 nanotubes with a superhydrophilic surface exhibit more excellent biological activity than pure titanium implants. However, the effects of the hydrogenated TiO2 nanotubes on human gingival epithelial cells remain unclear. Here, we fabricated hydrogenated TiO2 nanotubes using anodization and hydrogenation to investigate the adhesion of human gingival epithelial cells (HGEs) on structured surfaces in vitro. The topography, roughness, and wettability of three sample types—titanium (Ti), TiO2 nanotubes (TNTs), and hydrogenated TiO2 nanotubes (H2-TNTs)—were characterized. To evaluate cell adhesion, the HGEs were co-cultured with these specimens. This allowed for the examination of both the adhesion morphology and the number of cells adhering to each material’s surface. Expression levels of genes and proteins related to cell adhesion were also assessed. H2-TNTs demonstrated nanoscale topography similar to TNTs in terms of diameter and height and maintained a superhydrophilic surface (with a static water contact angle of < 5°). The number of HGEs adhering to H2-TNTs was notably higher. Furthermore, HGEs on H2-TNTs displayed a more stretched morphology in comparison to the other two groups. Notably, the expression levels of adhesion-related genes and proteins in H2-TNTs surpassed those of the other two groups. Hence superhydrophilic H2-TNTs significantly enhance the adhesion ability of HGEs on the material surface.
Location of the critical slip surface based on monitoring data and genetic algorithm
Authors: Fan Zhiyong , Lu Xiaobing , Zhao Ying , Liu Tianping , Liu Xiaoyu
Published: April 2024

The non-circular search limit equilibrium method (LEM) is a significant methodology in the analysis of slope stability, aimed at identifying the critical slip surface (CSS) and the safety factor (SF). However, the existing LEM does not consider monitoring data, such as the subsurface displacement, in the CSS search process for the actual slopes. In this paper, a new approach is proposed that combines LEM with subsurface displacement data to more accurately identify the CSS. The k-means clustering algorithm is utilized to determine the recognizing slip positions corresponding to each subsurface displacement curve. Additionally, the Spencer’s method is employed to calculate the SF. By treating the recognizing slip positions as constraint conditions, the genetic algorithm (GA) is applied to search for the location of the CSS. To validate the accuracy and usefulness of the proposed method, four numerical examples and an experimental case are presented.
Simulation of 1D atmospheric pressure dielectric barrier discharge in argon
Authors: Crispim L W S , da Silva C D , Amorim J , Ballester M Y
Published: April 2024

This work aims at modelling an atmospheric-pressure homogeneous barrier discharge in argon, using a time-dependent 1D fluid model coupled to the electric field and plasmo-chemical kinetic equations. The model is chosen to mimic a discharge when a sinusoidal 1 kV voltage at 10 MHz is applied to the terminals. Energy and mass transfer are considered for a macroscopic fluid representation, while energy transfer in molecular collisions and chemical reactions is treated at the microscopic level. The macroscopic model is represented by a set of coupled partial differential equations. Microscopic effects are studied within a discrete model for electronic and molecular collisions in the frame of ZDPlasKin, a plasma modelling numerical tool. The BOLSIG+ solver is employed in solving the electronic Boltzmann equation. An operator splitting technique is used to separate microscopic and macroscopic models. The spatial and temporal evolution of such species and electron transport parameters are presented and discussed.
Fuzzy-fractional modeling and simulation of electric circuits using extended He-Laplace-Carson algorithm
Authors: Qayyum Mubashir , Ahmad Efaza
Published: April 2024

In literature, most of the electric circuits are found to be at integer order, which are unable to capture the involved uncertainties and memory effects. To understand these effects, the current study is focused on modeling and analysis of fuzzy-fractional

L

˜

C

˜

circuit,

R

˜

C

˜

circuit,

R

˜

L

˜

circuit, and

R

˜

L

˜

C

˜

circuit. Triangular fuzzy numbers (TFNs) are utilized to introduce uncertainties in circuits. The memory effect is considered through fractional derivative in Caputo sense. A hybrid homotopy perturbation method (HPM) is established for solution purpose, in which standard HPM is combined with Laplace-Carson transformation in fuzzy-Caputo sense. This leads to an excellent and well-organized approach to calculate numerical solutions in the aspect of fuzzy logic and fractional calculus. The results obtained through proposed approach are validated by comparing them with already existing results in literature. Residual errors are also calculated across the domain of

r

at fractional order to determine the convergence and stability of electric circuit models. To study the dynamics of inductor, resistor, and capacitor on current along with fractional and fuzzy parameters involved in the electric circuits, contour and three-dimensional plots are constructed. Several plots specifying the fuzzy membership function of models across various parameter values are also demonstrated. The results achieved through this study indicate that He-Laplace-Carson method can assist engineers and researchers when dealing with electric circuits characterized by fuzzy and fractional dynamics.
Sperimagnetic states in amorphous Gd
x
(FeCo)1-x
(0.2 ≤ x ≤ 0.3) alloys: insights from stochastic magnetic anisotropy analysis
Authors: Solov’yov S V , Chernov A I
Published: April 2024

Materials crucial for the advancement of magnetic recording technologies stand as pivotal elements in the development of a new generation of recording devices. Recent advancements in the manipulation of magnetization through laser pulses have underscored the significance of magnetic materials exhibiting robust magneto-optical properties. This study explores the manifestation of a sperimagnetic state in ferrimagnetic amorphous Gd
x
(FeCo)1−x
alloys utilizing a stochastic magnetic anisotropy approach. Phase diagrams ‘magnetic field’-‘temperature’ and temperature dependencies of magnetization and compensation point were calculated using the mean-field approximation for temperature range from 50 to 700 K and different stoichiometry of the alloy, namely 0.2 ≤ x ≤ 0.3. Accounting for the stochastic anisotropy intrinsic to rare earth ions, a distribution of magnetic moments within the amorphous solid is discerned. Notably, this distribution predominantly manifests at the fringes of a canted phase, constituting the sperimagnetic structure. We demonstrate a direct correlation between an increased variance in normally distributed anisotropy constants of rare earth ions and a corresponding augmentation in the standard deviation of magnetization within the sperimagnetic structure. These findings not only contribute to a deeper understanding of the interplay between material composition and magnetic properties but also provide valuable insights for the advancement of magnetic recording technologies.
Low-power and robust ternary SRAM cell with improved noise margin in CNTFET technology
Authors: Haq Shams ul , Abbasian Erfan , Khurshid Tabassum , Sharma Vijay Kumar
Published: April 2024

In this paper, a carbon nanotube field-effect transistor (CNTFET) based low power and robust ternary SRAM (TSRAM) cell with enhanced static noise margin (SNM) has been proposed. The proposed cell uses a low-power cell core and a stack of 2 CNTFETs to discharge the read bit line (RBL) to ground, unlike the previous SRAM designs which use read buffers or transmission gates (TG) to alter the voltage levels on the RBL. The proposed TSRAM cell has been simulated relentlessly, using the Stanford 32 nm CNTFET technology mode file with Synopsis HSPICE tool under various operating conditions. Unlike other designs, the cross-coupled ternary inverters used as the cell core in the proposed TSRAM show higher gain and steep curves in the transition region mitigating the static power of the cell. The simulation results exhibit improvements in performance parameters like power consumption, energy, noise margins, and reliability. At 0.9 V supply voltage, the proposed TSRAM cell offers 52.44% and 43.17% reduction in write and read static power, a PDP reduction of 35.29% in comparison, and a 36.36% improvement in SNM compared to the best designs under investigation. Also, the proposed TSRAM design shows higher robustness compared to other designs.
Impact of B4C buffer layer on interface diffusion in Cr/Sc multilayers: combined study by x-ray reflectivity, scattering and fluorescence
Authors: Sarkar P , Biswas A , Rai Sanjay , Modi M H , Ghorai Gurupada , Sahoo Pratap K , Jha S N , Bhattacharyya D
Published: April 2024

In thin film multilayer based optical componentsof x-ray imaging system, diffusion of one material into the other degrades the reflectivity of the mirrors severely. Along with this thermodynamically driven diffusion, there are also growth generated interface roughness of different special frequencies and microstructures which can increase the diffused scattering from the multilayer and reduce the resolution of an image. Generally grazing incidence x-ray reflectivity in specular geometry (specular GIXR) and diffused x-ray scattering measurement in rocking scan geometry yield information regarding microstructure and overall diffusion at the interfaces of a multilayer. In this paper it is shown that grazing incidence x-ray fluorescence (GIXRF) measurement in standing wave condition alongwith the above measurements can give precise information regarding element-specific diffusion at the interfaces of a multilayer structure. Periodic multilayers made of 75 Cr/Sc bilayers with bilayer thickness ∼4 nm with and without B4C barrier layer of 0.2 nm thickness at the interfaces have been prepared using ion beam sputtering system and characterized by GIXR, diffused x-ray scattering and GIXRF measurements using synchrotron x-ray radiation just above the Cr K-edge. From the above measurements, drastic reduction in interface diffusion of Cr and improvement of interface morphology after addition of B4C barrier layer at the interfaces of Cr/Sc multilayers have been observed which is also corroborated by cross-sectional transmission electron microscopy of the multilayers. Finally, in the water window soft x-ray region of 2.3–4.4 nm performance of these multilayers have been tested and the Cr/B4C/Sc multilayer with improved interface quality has been found to yield ∼30.8% reflectivity at 3.11 nm wavelength which is comparable with the best reported reflectivities in the literature at this wavelength.
A theoretical approach to study the frequency dependent dielectric behavior of breast cancer cells using AlN buffer-based AlGaN/GaN HEMT
Authors: Poonia Ritu , Bhargava Lava , Mohammad Bhat Aasif , Periasamy C
Published: April 2024

The present study reports the detection of healthy (MDA-10) and malignant cells (MDA-MB-231) associated with breast cancer using high-quality AlN buffer AlGaN/GaN HEMT with dual cavity structure formed by etching out the gate metal from source and drain sides under the gate region. The AlN buffer AlGaN/GaN HEMT provides better 2DEG confinement and large conduction band offset than GaN buffer. The proposed design is analysed at frequencies of 900 MHz and 10 GHz, as breast cells have distinct dielectric properties at different microwave frequencies. The variation in dielectric constant of the cavity region corresponding to biomolecular species will change the device’s electrical characteristics and hence can be used to detect breast cancer cells. In this work, the device sensing parameters considered for analysis are shift in threshold voltage and drain current sensitivity. The device performance has also been analyzed by optimizing cavity thickness and length to select the best design for the sensing. The effect of non-ideal conditions such as steric hindrance and probing is also studied by emulating these real time effects in simulation. The device shows a maximum drain current sensitivity of 29.94% for 20 nm of cavity thickness and 1 μm of the cavity length. The results depict that the proposed device design exhibits a highly sensitive response and can be promising alternate for future biosensing applications.
Study the structure of the low-lying states of 206Po
Authors: Kocheva D , Rainovski G , Jolie J , Beckers M , Blazhev A , Esmaylzadeh A , Fransen C , Gladnishki K A , Pietralla N , Scheck M , Spee F , Stoyanova M , Werner V , De Gregorio G , Gargano A , Brown B Alex
Published: April 2024

The nucleus 206Po was studied in the two proton transfer reaction 204Pb(16O,14C)206Po and the lifetime of the first excited 2+ state was determined by utilizing the Recoil Distance Doppler Shift method. The experimental results are compared with shell-model calculations based on different effective interactions. The calculations qualitatively reproduced the experimentally observed

B
(
E
2
;

2

1

+

→

0

1

+

)

value, suggesting that the

2

1

+

state of 206Po exhibits a collective nature. However, the employed effective interactions revealed some limitations, particularly in their description of the

4

1
,
2

+

states. These results emphasize the importance of understanding the properties of low-lying states, especially their evolution from single-particle dynamics to collective modes, in evaluating various effective nuclear interactions.