bluuebunny/crossref_metadata_2025 huggingface dataset:
Using convolutional neural networks to detect edge localized modes in DIII-D from Doppler backscattering measurements
Authors: Teo N. Q. X. , Hall-Chen V. H. , Barada K. , Ng R. J. H. , Gu L. , Yeoh A. K. , Pratt Q. T. , Garbet X. , Rhodes T. L.
Published: July 2024

In H-mode tokamak plasmas, the plasma is sometimes ejected beyond the edge transport barrier. These events are known as edge localized modes (ELMs). ELMs cause a loss of energy and damage the vessel walls. Understanding the physics of ELMs, and by extension, how to detect and mitigate them, is an important challenge. In this paper, we focus on two diagnostic methods—deuterium-alpha (Dα) spectroscopy and Doppler backscattering (DBS). The former detects ELMs by measuring Balmer alpha emission, while the latter uses microwave radiation to probe the plasma. DBS has the advantages of having a higher temporal resolution and robustness to damage. These advantages of DBS diagnostic may be beneficial for future operational tokamaks, and thus, data processing techniques for DBS should be developed in preparation. In sight of this, we explore the training of neural networks to detect ELMs from DBS data, using Dα data as the ground truth. With shots found in the DIII-D database, the model is trained to classify each time step based on the occurrence of an ELM event. The results are promising. When tested on shots similar to those used for training, the model is capable of consistently achieving a high f1-score of 0.93. This score is a performance metric for imbalanced datasets that ranges between 0 and 1. We evaluate the performance of our neural network on a variety of ELMs in different high confinement regimes (grassy ELM, RMP mitigated, and wide-pedestal), finding broad applicability. Beyond ELMs, our work demonstrates the wider feasibility of applying neural networks to data from DBS diagnostic.
Density unstable fluid displacement in vertical annuli
Authors: Ghorbani M. , Zhang R. , Giljarhus K. E. T. , Skadsem H. J. , Frigaard I. A.
Published: July 2024

We study displacement flows involving pairs of Newtonian and shear-thinning fluids in vertical annular geometries using experimental and computational methods. This investigation is motivated by the primary cementing of casing strings, which is part of the well construction operation. In displacement scenarios that involve density-unstable fluid pairs, it is well-known that buoyancy can increase the inter-mixing between fluids and hence contaminate cementing fluids due to gravity-driven instabilities. Our study seeks to investigate how the imposed flow rate, the degree of inner pipe centralization, and the viscosity of the fluids affect the displacement efficiency in such cases. The study complements our recent paper [R. Zhang et al., “Vertical cementing displacement flows of shear-thinning fluids,” Phys. Fluids 35, 113110 (2023)], which focused on density-stable configurations, and here we consider the more challenging, density-unstable displacement flows. Our experiments and three-dimensional computational results are in general agreement. The results show that displacements improve for viscosity-stable conditions, i.e., when the displacing fluid is the more viscous fluid. Characteristic fingering patterns occur in the interface region of the fluids for viscosity-unstable conditions. The eccentricity of the inner pipe is seen to promote the channeling of fluids, and viscosity-unstable conditions can exacerbate this effect further. A degree of stabilization of density unstable displacements can be achieved by increasing the imposed flow rate and the viscosity of the fluids while maintaining a stable viscosity ratio.
Compressive strain-induced enhancement of thermoelectric performance in lead-free halide double perovskites K2SnX6 (X = I, Br, Cl)
Authors: Jong Un-Gi , Kim Su-Hyang , Ham Ryong-Wan , Ri Song , Ri Ryong-Jin , Yu Chol-Jun
Published: July 2024

Exploring thermoelectric materials with high performance and low cost is of great importance in mitigating environmental and energy challenges. Here, we provide an atomistic insight into strain-induced enhancement of thermoelectric performance in potassium-based halide double perovskite K2SnX6 (X = I, Br, Cl) using first-principles calculations. To get reliable predictions for transport properties, we adopt advanced methods such as self-energy relaxation time approximation for electron transport and unified theory for lattice transport in combination with self-consistent phonon approach. Our calculations highlight a promising thermoelectric figure of merit ZT over 1.01 in K2SnI6 when applying a compressive strain of −6%, being tenfold larger than those in the uncompressed compounds, suggesting that compressing is an effective way to enhance the thermoelectric performance of halide double perovskites.
Reduced trap state density in AlGaN/GaN HEMTs with low-temperature CVD-grown BN gate dielectric
Authors: He Ziyi , Zhang Xiang , Pieshkov Tymofii S. , Yekta Ali Ebadi , Terlier Tanguy , Mudiyanselage Dinusha Herath , Wang Dawei , Da Bingcheng , Xu Mingfei , Luo Shisong , Chang Cheng , Li Tao , Nemanich Robert J. , Zhao Yuji , Ajayan Pulickel M. , Fu Houqiang
Published: July 2024

In this Letter, low-temperature (400 °C) chemical vapor deposition-grown boron nitride (BN) was investigated as the gate dielectric for AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MISHEMTs) on a Si substrate. Comprehensive characterizations using x-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy, atomic force microscope, high-resolution transmission electron microscopy, and time-of-flight secondary ion mass spectrometry were conducted to analyze the deposited BN dielectric. Compared with conventional Schottky-gate HEMTs, the MISHEMTs exhibited significantly enhanced performance with 3 orders of magnitude lower reverse gate leakage current, a lower off-state current of 1 × 10−7 mA/mm, a higher on/off current ratio of 108, and lower on-resistance of 5.40 Ω mm. The frequency-dependent conductance measurement was performed to analyze the BN/HEMT interface, unveiling a low interface trap state density (Dit) on the order of 5 × 1011–6 × 1011 cm−2 eV−1. This work shows the effectiveness of low-temperature BN dielectrics and their potential for advancing GaN MISHEMTs toward high-performance power and RF electronics applications.
Time-dependent electron Boltzmann equation for hypersonic plasmas
Authors: Petrov George M. , Petrova Tzvetelina B. , Peñano Joseph R.
Published: July 2024

The electron kinetics in hypersonic plasmas is modeled by solving the time-dependent electron Boltzmann equation for the electron energy distribution function (EEDF). This plasma is created by strong shock compression of the gas in front of a vehicle moving with hypersonic speed. The main source of energy for the electrons is gas heating due to elastic collisions and second-kind collisions (de-excitation) from vibrationally excited states of N2. We established that the electron energy distribution function is most sensitive to vibrational level populations. At mid-altitudes (tens of kilometers), the electron temperature equilibrates with the vibrational temperature on a microsecond timescale. The electron distribution function reaches steady state on a comparable timescale. Numerical simulations of air plasma showed that the electron energy distribution function is far from Maxwellian and the collision rates differ by orders of magnitude from those computed with a Maxwellian distribution. The two most important parameters for the electron kinetics and the electron energy distribution function are the vibrational temperature and ionization degree.
Implementation of low temperature spectrometers for the JET high resolution Thomson scattering diagnostic for disruption plasma measurements
Authors: Huang Z. , Kos D. , Maslov M. , Scannell R. , Clark J. , Ficker O. , Jachmich S. , Lehnen M. , Reux C. , Sheikh U. ,   The JET Contributors
Published: July 2024

This work presents a system upgrade of the High Resolution Thomson Scattering (HRTS) diagnostic [Pasqualotto et al., Rev. Sci. Instrum. 75, 3891–3893 (2004)] on JET that allows it to measure low temperature (1–500 eV) plasma pre- and post-Thermal quench (TQ), which would help us further understand the Shattered Pellet Injection (SPI) physics. The upgrade was done by connecting optic fibers from the original HRTS system to four spectrometers specialized in measuring low temperature plasmas. The upgraded system allows for the measurement of low temperature plasma at up to 12 spatial points, which can be flexibly distributed throughout the JET outer midplane profile during the dedicated SPI experiments. In other JET experiments, four previously unused groups of fibers were used to measure the central plasma to provide disruption data without changing the standard HRTS system. The low temperature Thomson scattering system was installed, commissioned, and cross-calibrated against the standard HRTS diagnostic in a calibration pulse. The system worked reliably during the JET experiments and provided electron density and temperature profiles for pre- and post-TQ low temperature plasmas in the SPI campaign.
Drivers of international fire management personnel deployed to the United States
Authors: Bloem Sunniva , Cullen Alison C. , Abatzoglou John T. , Mearns Linda O. , Belval Erin
Published: July 2024

Background The rising occurrence of simultaneous large wildfires has put strain on United States national fire management capacity leading to increasing reliance on assistance from partner nations abroad. However, limited analysis exists on international resource-sharing patterns and the factors influencing when resources are requested and deployed. Aims This study examines the drivers of international fire management ground and overhead personnel deployed to the United States. Methods Using descriptive statistics and case examples data from 2008 to 2020, this study investigates the conditions under which international personnel are deployed to the United States and their relationship to domestic resource strain. Factors such as fire weather, fire simultaneity, and the impact on people and structures are analysed as potential drivers of demand for international resources. Additionally, barriers to resource sharing, including overlapping fire seasons between countries are examined. Key results The findings indicate that international personnel sharing is more likely when the United States reaches higher preparedness levels, experiences larger area burned, and when fires pose a greater impact on people and structures. However, overlapping fire seasons can limit the ability to share resources with partner nations. Conclusions and implications Understanding the factors influencing resource sharing can help improve collaboration efforts and enhance preparedness for future wildfire seasons.
Biofortification: Conventional Plant Breeding to Increase the Nutrient Density of Commonly Consumed Staple Foods
Authors: Walton Jenny
Published: July 2024

One in two children and two in three women worldwide are likely to have at least one micronutrient deficiency and many suffer from more than one. Around 60% of the world calorie intake comes from the major staples, wheat, rice and maize and many more calories come from local staples such as beans, cassava, millets and potatoes. These staples provide the perfect means to deliver more micronutrients into the diets of millions of people. Biofortification through plant breeding can improve the micronutrient content of the world’s favourite staples and CGIAR (formerly the Consultative Group for International Agricultural Research), through the HarvestPlus project, has put this theory into practice by reaching up to 330 million consumers in Latin America, Africa and Asia. While this seems like a large number, work is required to sustainably embed the intervention and to scale it to all consumers using an agriculturally based strategy that will remain in commercial food systems for generations to come.

Information

© The Author 2024
Murine glial protrusion transcripts predict localized Drosophila glial mRNAs involved in plasticity
Authors: Lee Jeffrey Y. , Gala Dalia S. , Kiourlappou Maria , Olivares-Abril Julia , Joha Jana , Titlow Joshua S. , Teodoro Rita O. , Davis Ilan
Published: July 2024

The polarization of cells often involves the transport of specific mRNAs and their localized translation in distal projections. Neurons and glia are both known to contain long cytoplasmic processes, while localized transcripts have only been studied extensively in neurons, not glia, especially in intact nervous systems. Here, we predict 1,740 localized Drosophila glial transcripts by extrapolating from our meta-analysis of seven existing studies characterizing the localized transcriptomes and translatomes of synaptically associated mammalian glia. We demonstrate that the localization of mRNAs in mammalian glial projections strongly predicts the localization of their high-confidence Drosophila homologs in larval motor neuron–associated glial projections and are highly statistically enriched for genes associated with neurological diseases. We further show that some of these localized glial transcripts are specifically required in glia for structural plasticity at the nearby neuromuscular junction synapses. We conclude that peripheral glial mRNA localization is a common and conserved phenomenon and propose that it is likely to be functionally important in disease.
Transformer coupled toroidal wave-heated remote plasma sources operating in Ar/NF3 mixtures
Authors: Doyle Scott J , Larson Amanda , Rosenzweig Guy , Gunn James , Kushner Mark J
Published: July 2024

Remote plasmas are used in semiconductor device manufacturing as sources of radicals for chamber cleaning and isotropic etching. In these applications, large fluxes of neutral radicals (e.g. F, O, Cl, H) are desired with there being negligible fluxes of potentially damaging ions and photons. One remote plasma source (RPS) design employs toroidal, transformer coupling using ferrite cores to dissociate high flows of moderately high pressure (up to several Torr) electronegative gases. In this paper, results are discussed from a computational investigation of moderate pressure, toroidal transformer coupled RPS sustained in Ar and Ar/NF3 mixtures. Operation of the RPS in 1 Torr (133 Pa) of argon with a power of 1.0 kW at 0.5 MHz and a single core produces a continuous toroidal plasma loop with current continuity being maintained dominantly by conduction current. Operation with dual cores introduces azimuthal asymmetries with local maxima in plasma density. Current continuity is maintained by a mix of conduction and displacement current. Operation in NF3 for the same conditions produces essentially complete NF3 dissociation. Electron depletion as a result of dissociative attachment of NF3 and NF
x
fragments significantly alters the discharge topology, confining the electron density to the downstream portion of the source where the NF
x
density has been lowered by this dissociation.
High energy density of biaxially oriented polypropylene film in cryogenic environment for advanced capacitor
Authors: Du Bo Xue , Chen Ke , Liu Haoliang , Xiao Meng
Published: July 2024

In this paper, a method of significantly increasing the energy density of biaxially oriented polypropylene (BOPP) film by cryogenic environment has been proposed. The notable enhancements in the dielectric and energy storage performance can be attributed to precise microstructure manipulation, aimed at controlling charge injection limitations and optimizing molecular chain dynamics. The experimental results show that the maximum discharged energy density of BOPP film with thicknesses of 3.4 μwm has reached 11.83 J cm−3 at −196 °C (2.9 times that at 25 °C) with a charge-discharge efficiency of 92.74%. The direct current breakdown strength as high as 1120.4 kV mm−1 is obtained at −196 °C, exhibiting a substantial 63.7% augmentation compared to the measurement at 25 °C. Furthermore, reductions in conductance loss and capacitance loss (post self-healing testing) are realized. Mechanistic insights into the observed enhancements are investigated through computational simulations. This research provides a pivotal advancement and valuable perspective towards the development of film capacitors boasting the excellent energy storage characteristics.
Unveiling photon–photon coupling induced transparency and absorption
Authors: Shrivastava Kuldeep Kumar , Sahu Ansuman , Bhoi Biswanath , Singh Rajeev
Published: July 2024

This study presents the theoretical foundations of analogous electromagnetically induced transparency and absorption, which we refer to as coupling induced transparency (CIT) and absorption (CIA), respectively, along with an exploration of the transition between these phenomena. We provide a concise phenomenological description with analytical expressions for transmission spectra and dispersion, elucidating how the interplay of coherent and dissipative interactions in a coupled system results in the emergence of level repulsion (LR) and attraction (LA), corresponding to CIT and CIA, respectively. This theory comprehensively captures both the phenomena while modelling the microstrip line loaded resonators and their couplings systematically. The model is validated through numerical simulations using a hybrid system comprising a split ring resonator (SRR) and an electric inductive-capacitive (ELC) resonator in planar geometry. We analyse two cases while keeping the ELC parameters constant, one involving a dynamic adjustment of the SRR size with a fixed split gap, and the other entailing a varying gap while maintaining a constant SRR size. Notably, in the first case, the dispersion profile of the transmission signal demonstrates LR, while the second case results in LA, effectively showcasing CIT and CIA, respectively. These simulated findings not only align with the theoretical model but also underscore the versatility of our approach. Subsequently, we extend our model to a more general case, demonstrating that a controlled transition from CIT to CIA is achievable by manipulating the dissipation rate of individual modes within the hybrid system, leading to either coherent or dissipative interactions between the modes. Our results provide a pathway for designing hybrid systems that can control the group velocity of light, offering potential applications in the fields of optical switching and quantum information technology.
A two-step bearing fault diagnosis strategy under variable speed based on symplectic geometry modal decomposition and practical fault feature extraction framework
Authors: Huang Shuai , Li Junxia , Wang Yandong , Qin Zhixiang
Published: July 2024

Abstract

Strong noise interference can lead to failure of bearing fault diagnosis techniques. This paper proposes a two-step fault diagnosis strategy to address the challenge of weak fault feature extraction in bearing fault diagnosis using acoustic or vibration data at varying speed. Firstly, the paper introduces a short-time symplectic modal decomposition (stSGMD) method that utilizes fractional Fourier transform (FrFT). This method involves signal processing with short-time windowing to extract fault-sensitive components. The window is then expanded to obtain the complete component through fractional Fourier domain (FrFD) narrow-band filtering based on energy concentration in the FrFD. A novel entropy index, named standard deviation discrete entropy (SDDE), is introduced to quantify the intensity of fault shocks in non-stationary signal and is used to select components in the stSGMD. Subsequently, a fault feature extraction framework called global objective deconvolution (GOD) is presented for extracting instantaneous fault features at varying speed. This method establishes a global objective matrix for the extraction process. The GOD is utilized to deconvolute the complete fault-sensitive component, followed by envelope order analysis for demodulating the fault feature order. Numerical simulations and experimental studies on acoustics and vibration are performed. The results demonstrate that stSGMD improves the demodulation capability of SGMD, while GOD effectively extracts fault features. It is expected that the presented method will be effectively utilized for fault feature extractions in bearings operating under linear variable speed conditions.
Lower magnetic field measurement limit of the coupled dark state magnetometer
Authors: Ellmeier Michaela , Betzler Alexander , Amtmann Christoph , Pollinger Andreas , Hagen Christian , Jernej Irmgard , Agú Martín , Magnes Werner , Windholz Laurentius , Dougherty Michele , Brown Patrick , Lammegger Roland
Published: July 2024

The Coupled Dark State Magnetometer (CDSM) is an optically pumped magnetometer. For the Jupiter Icy Moons Explorer mission, the CDSM and two fluxgate magnetometers are combined in the J-MAG instrument to measure the static and low frequency magnetic field in the Jupiter system. During certain calibration manoeuvres, the CDSM has to be able to measure magnetic field strengths down to 100 nT with an accuracy of 0.2 nT (

1

σ

). At such low magnetic fields, the CDSM’s operational parameters must be carefully selected to obtain narrow resonance structures. Otherwise, the coupled dark state resonances, used for the magnetic field detection in different instrument modes, overlap and result in a systematic error. The overlap of the resonances and therefore the systematic error mainly depends on the resonance line width and the selected modulation frequencies for the detection of the resonances. We show that a line width of less than 200 Hz and selecting a modulation frequency of about the resonance line width are beneficial at magnetic field strengths

B
<
1.5

μ

T. In this paper we demonstrate that with the found instrument settings the CDSM is able to measure magnetic field strengths below 100 nT with a systematic error less than 0.2 nT resulting from the overlap of the resonances.
Bayesian reconstruction of 3D particle positions in high-seeding density flows
Authors: Hans Atharva , Bhattacharya Sayantan , Hao Kairui , Vlachos Pavlos , Bilionis Ilias
Published: July 2024

Measuring particles’ three-dimensional (3D) positions using multi-camera images in fluid dynamics is critical for resolving spatiotemporally complex flows like turbulence and mixing. However, current methods are prone to errors due to camera noise, optical configuration and experimental setup limitations, and high seeding density, which compound to create fake measurements (ghost particles) and add noise and error to velocity estimations. We introduce a Bayesian volumetric reconstruction (BVR) method, addressing these challenges by using probability theory to estimate uncertainties in particle position predictions. Our method assumes a uniform distribution of particles within the reconstruction volume and employs a model mapping particle positions to observed camera images. We utilize variational inference with a modified loss function to determine the posterior distribution over particle positions. Key features include a penalty term to reduce ghost particles, provision of uncertainty bounds, and scalability through subsampling. In tests with synthetic data and four cameras, BVR achieved 95% accuracy with less than 3% ghost particles and an RMS error under 0.3 pixels at a density of 0.1 particles per pixel. In an experimental Poiseuille flow measurement, our method closely matched the theoretical solution. Additionally, in a complex cerebral aneurysm basilar tip geometry flow experiment, our reconstructions were dense and consistent with observed flow patterns. Our BVR method effectively reconstructs particle positions in complex 3D flows, particularly in situations with high particle image densities and camera distortions. It distinguishes itself by providing quantifiable uncertainty estimates and scaling efficiently for larger image dimensions, making it applicable across a range of fluid flow scenarios.
AFO-SLAM: an improved visual SLAM in dynamic scenes using acceleration of feature extraction and object detection
Authors: Wei Jinbi , Deng Heng , Wang Jihong , Zhang Liguo
Published: July 2024

In visual simultaneous localization and mapping (SLAM) systems, traditional methods often excel due to rigid environmental assumptions, but face challenges in dynamic environments. To address this, learning-based approaches have been introduced, but their expensive computing costs hinder real-time performance, especially on embedded mobile platforms. In this article, we propose a robust and real-time visual SLAM method towards dynamic environments using acceleration of feature extraction and object detection (AFO-SLAM). First, AFO-SLAM employs an independent object detection thread that utilizes YOLOv5 to extract semantic information and identify the bounding boxes of moving objects. To preserve the background points within these boxes, depth information is utilized to segment target foreground and background with only a single frame, with the points of the foreground area considered as dynamic points and then rejected. To optimize performance, CUDA program accelerates feature extraction preceding point removal. Finally, extensive evaluations are performed on both TUM RGB-D dataset and real scenes using a low-power embedded platform. Experimental results demonstrate that AFO-SLAM offers a balance between accuracy and real-time performance on embedded platforms, and enables the generation of dense point cloud maps in dynamic scenarios.
Anti-slosh effect of baffle configurations and air pressure on liquid sloshing in partially filled tank trucks
Authors: Wang Qiongyao , Ping Kai , Xu Wenhua , Huang Jiarong , Tan Lingcao
Published: July 2024

The phenomenon of liquid sloshing inside partially filled tank trucks adversely affects the stability of the tank trucks. In order to mitigate the negative effects of liquid sloshing inside the tank, this study proposes several baffle configurations and investigates their anti-slosh effect on liquid sloshing. First, a numerical model of liquid sloshing is established. Then, the effectiveness of the numerical model is validated by comparing the results of free surface deformation, wall pressure, and sloshing frequency obtained from simulations and experiments under identical conditions. During the research process, it was found that the air pressure formed in locally sealed spaces within the tank also plays a positive role in suppressing liquid sloshing. The research results indicate that, under low fill volumes, baffles fixed at the bottom of the tank are more effective in suppressing liquid sloshing inside the tank, while under high fill volumes, baffles fixed at the top of the tank are more effective. Considering the tank’s airtightness, the air pressure formed in locally sealed spaces within the tank plays an important role in suppressing liquid sloshing when baffles are fixed at the top of the tank and the fill volume is high.
Study on the tribocharging properties of MgCO3 particles based on LFN-en-A model
Authors: Su Meixuan , Yang Zhipeng , Cai Kewei , Wang Zhiqiang , Yang Song , Li Guofeng
Published: July 2024

As an efficient and environment-friendly method, electrostatic separation has gradually replaced flotation methods in the separation of magnesite in recent years. In the process of triboelectrostatic separation, the mineral particles are tribocharged driven by the air flow, then the trajectory is shifted under the action of the electric field, so as to realize the separation. The useful mineral in magnesite is MgCO3, but the theoretical research related to the charge characteristics of MgCO3 is not sufficient. Particle image velocimetry (PIV), as an indirect measurement technique, is able to obtain the velocity field of the fluids from images. However, the particles moving in the air have the issues such as excessive speed and small particle size, which make the traditional PIV has low accuracy in estimating the motion of particles. In this paper, a high-speed camera is used to capture the motion trajectory of tribocharged MgCO3 particles in a parallel electric field. A new optical flow method LFN-en-A network based on LiteFlowNet-en network is proposed to compute the particle motion trajectory by combining the deep learning method with the traditional PIV, which realizes the displacement estimation of particles moving in the air. It ultimately realizes the calculation of the charge-to-mass ratio on single particles. Analyzing the accuracy of the LFN-en-A network’s estimation in the experiments, the estimation of LiteFlowNet-en was compared. Changing the shooting frame rate analyzes the optimal one required by the LFN-en-A network. Combining the estimation results of LFN-en-A to calculate the particle charge-to-mass ratio (Q/m), the Q/m of MgCO3 particle was analyzed by changing the experimental conditions in the process of particles’ tribocharging, which provided a new method for particle-to-charge ratio measurement.
Wavelength-influenced electrical performance of laser-written flexible copper-based structures
Authors: Liu Tong , Zhu Ying , Guo Wei , Zhang Hongqiang , Sun Qian , Jia Qiang , Zhou Xingwen
Published: July 2024

The one-step direct laser writing process has been an efficient strategy for constructing flexible metal structures. However, the effect of laser wavelength on the structuring process remains unclear, thus restricting the universal manufacturing process development. In this work, the feasibility of one-step writing of flexible Cu structures with different wavelength continuous diode lasers has been verified. Here, photothermal reactions dominate in the decomposition of the reducing agent to form copper structures. Differences in the wavelength primarily affect the photothermal reaction amplitude for structuring, resulting in a variation in the formation of Cu structures. Under our processing conditions, the photothermal reaction induced by 532 nm laser is higher than 808 nm laser, a higher reduced-joining degree of the Cu structure can be achieved by 532 nm laser. This results in a superior conductivity, adhesion, and bendability of Cu structures fabricated by 532 nm laser than that of 808 nm laser. Furthermore, strain sensors that can detect different bending angles and bending frequencies have been fabricated by 532 nm laser-written structures to demonstrate their practical applications.
Effects of liquid lubricants on the surface characteristics of 3D-printed polylactic acid
Authors: Kim Gang-Min , Lee Sung-Jun , Kim Chang-Lae
Published: July 2024

In this study, 3D-printed Polylactic acid (PLA) specimens were manufactured and polished using various lubricants to assess their surface, friction, and wear characteristics. After polishing, the surface roughness decreased by approximately 80% compared with that before polishing, except when acetone was used as the lubricant. In particular, under deionized (DI) water and acetone lubrication conditions, the friction coefficient decreased by 63% and 70%, respectively, whereas the specific wear rate decreased by 88% and 83%, respectively, compared with the unpolished specimens. In the case of dry polishing, adhesion, friction, and wear increase owing to surface damage. Ethanol and IPA polishing resulted in hydrolysis and increased friction, but slightly decreased wear rates. The surface of the specimen polished with acetone dissolved and became very rough. Only the surface polished with DI water exhibited hydrophobic properties. When acetone and DI water were used as lubricants, the surface adhesion force, adhesion energy, friction coefficient, and wear rate were lowest. The finite element analysis results showed that the polished surface exhibited stable contact pressure and friction force, while the unpolished surface showed large fluctuations in contact pressure and friction force owing to the laminated pattern. These results suggest that the polishing process is crucial for improving the surface characteristics and mechanical performance of 3D-printed PLA parts.
Error analysis for determining transverse tensile delamination strength of REBCO coated conductors by anvil test: numerical simulation demonstrations
Authors: Gao Peifeng , Zhang Yameng , Lin Xiaohui , Chen Sikan , Zhu Jiamin , Guan Mingzhi , Wang Xingzhe
Published: July 2024

RE–Ba–Cu–O (REBCO, where RE = Y, Gd, Sm, and other rare earth elements) coated conductor (CC) tapes exhibit considerable potential for application within the domains of high-energy physics and high-field science. Nevertheless, weak interfacial properties pose a significant obstacle, impeding the progress and practical implementation in high-field scenarios. The anvil tension method has been extensively employed for the assessment of transverse delamination strength of REBCO CC tapes. However, the outcomes derived from anvil tension exhibit severe dispersion, thereby impeding its efficacy in evaluating material performance. The underlying cause of this phenomenon remains unidentified. In this study, error analysis of anvil measurement method in determining the transverse tensile delamination strength (TTDS) of REBCO CC tapes was conducted based on finite element (FE) numerical simulations. A two-dimensional multilayer elastic-plastic delamination FE model with main layers of REBCO CC tapes, solder connecting layers and anvil materials were developed based on the bilinear cohesive zone model. The effects of anvil test conditions and the structural configuration of the conductor itself on the test results were discussed. Simulation results show that localized premature cracking of the interface due to stress concentration and plastic yielding of the CC tape around the loading boundary is the root reason for the discrepancy between the anvil test results and the true interfacial strength. Therefore, anvil test conditions (including top anvil dimensions, soldering conditions, loading eccentricity angle, and anvil material properties) as well as the structural configuration of the conductor itself (including edge initial crack length, edge encapsulation width, and stabilizer thickness) have a significant impact on anvil test-based TTDS results.
Deep insight of inter-channel coupling in AlGaN/GaN double channel HEMT and its application in C-ERB2 sensing
Authors: Kanrar Sharmistha Shee , Sarkar Subir Kumar
Published: July 2024

AlGaN/GaN Double Channel High Electron Mobility Transistors (DCHEMTs) have emerged as promising biosensors, leveraging the unique properties of inter-channel coupling. This paper investigates the influence of mole fraction variations in the AlGaN layer on inter-channel coupling and explores its implications for C-ERB2 biosensing. The study reveals the potential of inter-channel coupling to enhance sensitivity in biosensing applications, particularly for detecting C-ERB2, a crucial protein associated with various cancers. The device architecture, simulation models, electrostatics, and sensitivity analysis are comprehensively examined. The findings underscore the significance of inter-channel coupling in optimizing biosensor performance, offering valuable insights for the advancement of biosensing technologies.
Point and interval estimation based on joint progressive censoring data from two Rayleigh-Weibull distribution with applications
Authors: M Hasaballah Mustafa , Samson Balogun Oluwafemi , Bakr M E
Published: July 2024

The exploration of progressively censored data has garnered considerable attention in recent years. This research delves into the joint progressive censoring scheme applied to two populations. It presupposes that the lifespan distribution of items from these populations follows Rayleigh-Weibull distributions, characterized by varying shape and scale parameters. Within the framework of the joint progressive censoring scheme, we investigate maximum likelihood estimators for unknown parameters wherever applicable. Bayesian inferences for these parameters are presented using a Gamma prior. It’s worth noting that deriving Bayes estimators and their associated credible intervals is not feasible, hence we suggest employing the importance sampling technique for computation. To illustrate the methodologies, we analyze real-life data for demonstrative purposes, and Monte Carlo simulations are carried out to compare the performances of all the proposed methods.
Solution of state transfer matrix based on DNA strand displacement circuits
Authors: Ling Dan , Su Hao , Sun Ce , Sun Junwei , Wang Yanfeng
Published: July 2024

In recent years, DNA strand displacement (DSD) circuits have been developed in leaps and bounds. The high storage and parallelism of DNA give it an inherent advantage in the field of DNA computations. DSD is widely used in analog computations and neural network computations. However, there are few studies on solving state transfer matrix using DSD circuits. Aiming at the above problems, a scheme for solution of state transfer matrix based on DSD circuits is proposed. In this paper, the summation, subtraction, multiplication, division and exponential reaction modules are built by the DSD reactions. Based on the reaction modules, DNA chemical reaction networks of state transfer matrix are constructed. DSD circuits are built by cascading the DNA chemical reaction networks. The solution of the state transfer matrix is implemented through the DSD circuits. The Visual DSD is used to verify the practicality of DSD circuits. This scheme may provide a reference to analog computations based on DSD circuits.
Tunable terahertz filter based on graphene photonic crystals with defective layers
Authors: Shen Songchao , Hameed Ahmed M F , Qin Feifei , Ibrar  , Bian Ang , Dai Jun
Published: July 2024

In this paper, we design a high-precision tunable terahertz filter by using transfer matrix method. The filter structure mainly consists of graphene embedded photonic crystals (GPCs). The front part of the GPCs contains artificial synthetic material and air layer, the back part of the GPCs is composed by and periodic stack of isotropic dielectric slabs (MgF2) embedded with graphene sheets, where air defect layer is located in the middle of the GPC as a central layer. Our simulation reveals that graphene layer and air defective layer strongly affect the filter performance. And we can get a relatively pure transmission peak in a wide frequency region. Additionally, the influence of incidence angle of terahertz wave, thickness of air layer, the unit number of front periodic structure and chemical potential of the graphene sheets can also modulate the function of the filter. And the filter has strong stability when the temperature changes from 150 K to 350 K.The results indicate that single channel, dual and multiple channels filter in a narrow frequency can be obtained by optimizing the structure parameter.
Fabrication, structural, morphological, and mechanical behaviour of fly ash doped clay ceramics based CO2 gas sensor
Authors: Kumari Savita , Rakhi  , Hussain Ajaz , Avinashi Sarvesh Kumar , Mishra Rajat Kumar , Shweta  , Singh Ajeet , Yadav Bal Chandra , Gautam Chandkiram
Published: July 2024

Various attempts have been made to fabricate fly ash-doped clay composites via solid state reaction method. Additionally, to investigate the structural, mechanical, surface morphology, and CO2 gas sensing behavior, the fabricated clay composites were sintered at three different temperatures 1000, 1100, and 1200 °C (COF1, COF2, COF3) for 4 h. The green and sintered densities of the fabricated composites were found to be in the range of 2.17–2.13 g cm−3 and 1.38 to 1.30 g cm−3. Further, various characterization techniques such as x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, universal testing machine (UTM) and scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDAX) were carried out. Moreover, to determine the compressive strength and Young’s modulus values, a universal testing machine (UTM) was used. The fracture toughness of the fabricated composites, COF2 and COF3 were found to be 7.84 MPa-m1/2 and 2.22 MPa-m1/2. The COF3 composite exhibited a sensing response, response time, recovery time of 3.39 at 1200 ppm CO2, 16.95 s and 18.05 s respectively. Consequently, this porous clay composite can be fabricated in a cost-effective and eco-friendly manner, hence beneficial for CO2 gas sensing applications.
Complex partition function of 1-dimensional Dirac particle confined in Woods-Saxon interaction
Authors: Ibrahim T T , Oladimeji E O , Koffa D J , Edogbanya H O , Gwani M M , Omonile J F
Published: July 2024

We present the bound state solutions of one-dimensional Schrödinger and Dirac equations for a particle confined in Woods-Saxon potential. In each case the wavefunctions and the energy eigenvalues have been obtained in terms of the Jacobi polynomials by using the Nikiforov-Uvarov method. The complex eigenenergy obtained from the Dirac equation is explicitly shown to contain the nonrelativistic energies plus complex relativistic correction terms The quantum partition functions obtained using the relativistic and the nonrelativistic energies have been used to generate important thermodynamic properties of the system in the high temperature limit. In particular, the complex partition function obtained in the relativistic regime is taken to indicate some important physical effects in the system.
DLS homemade setup: reviewing first and second-order coherence and autocorrelation concepts of a light source in the context of nanoparticle sizes synthesized by PLAL
Authors: Meza-Arroyo J , Valdés-Hernández J , Domínguez-Juárez J L , Quintero-Torres R
Published: July 2024

The size of the nanoparticles (NP) is one of the most important and essential characteristics to know the properties of the synthesized nanostructures. The most common characterization procedures are related to Scanning Electronic Microscopy (SEM), Transmission Electronic Microscopy (TEM), and Atomic Force Microscopy (AFM). Unfortunately, from a practical point of view, they represent a time-consuming procedure and require expensive equipment, which limits its application to specialized research groups. Significant attention has been paid to Dynamic Light Scattering (DLS) as a simple, fast, and reproducible method for sizing nanoparticles. However, inadequate representation of the fundamental principles of DLS and data interpretation represents two of the most important challenges related to this technique. In this work we try to provide the fundamental principles of the DLS technique, the fundamental mathematical treatment of data obtained during the optical scattering studies and provide the MATLAB code to configure non-commercial DLS equipment. Additionally, analyzes of nanoparticles obtained by pulsed laser ablation of Ag, Au, Si and W and commercial Au nanoparticles were carried out. The particle size results are compared with SEM images to calculate the percentage error of the DLS measurements. The results show an error of 5%, 3.8%, 2.1% for the Ag, Au and Si nanoparticles respectively, which proves to be an excellent approximation to the real values of nanoparticle diameter. Meanwhile, the error in size for W nanoparticles by the same technique and commercial Au nanoparticle is 29% and 12%, which shows the effect of the hydrodynamic diameter of the nanoparticles. This work ends with the analysis of the concentration of nanoparticles and its importance in reliable results of DLS measurements.
A Digital Backend with Pulse Detection for Radar Astronomy
Authors: Li Gaojing , Meng Qiao , Ping Jingsong , Sun Jing , Yang Song , Zhou Chenye , Guo Shaocong , Wu Jie
Published: July 2024

In radar astronomy, the digital backend and data recording system process and store echo signals in real-time, facilitating the monitoring of near-earth objects such as space debris, satellites, and asteroids. In this paper, a radar astronomy digital backend (RADB), designed for radar astronomy observation and data recording, is proposed. With a sampling rate of 1.12 GSps, the RADB accommodates various analog intermediate frequency (IF) front-ends. In addition to continuously recording echo signals, the RADB has three pulse storage modes and employs an architecture that combines a two-stage decimation (TSD) unit and a decimated pulse detection (DPD) unit. The TSD unit reduces the sampling frequency based on the bandwidth of the signal, after shifting the IF signal to the baseband. Compared to a single-stage decimation, the proposed TSD structure effectively reduces FIR resource consumption without compromising performance. Meanwhile, the DPD unit identifies pulse echo signals and selectively enables the backend to store data only when pulses are detected. This process further reduces the burden on data transmission and storage. Furthermore, the matched filtering pulse detection method in the DPD unit enhances triggering performance, particularly under weak signal conditions. Preliminary performance evaluations in a laboratory demonstrate that the TSD unit reduces data volume by 56 times, while the DPD unit achieves a further reduction of 20 times. Concurrently, a Moon reflection experiment is also conducted at the Yunnan Kunming Electromagnetic Environment Observation and Research Station by using a 29 m antenna. Analysis and processing of stored data validate the effectiveness of the proposed design.
Machine learning assisted reconstruction of positron-on-target annihilation events in the PADME experiment
Authors: Dimitrova Kalina ,   PADME Collaboration
Published: July 2024

The PADME Experiment at the Laboratori Nationali di Frascati, INFN is used in the search for a Dark photon, produced with an ordinary photon in electron-positron annihilation events. The energy of the photons, emitted in the annihilation is measured using a segmented electromagnetic calorimeter. Machine learning methods consisting of various convolutional neural networks are used for the reconstruction of close-in-time signals with high resolution. These algorithms were used on two-photon annihilation events e
+
e
− → γγ to calibrate the photon energy values. In order to calibrate the neural network output from signal amplitude to energy, the machine learning based results were compared to the conventional methods used for reconstructing the signals. The use of machine learning models for reconstructing real data and the process of calibrating the machine learning method output are presented and discussed.
Solar physics and space weather research at the Institute of Astronomy and NAO - BAS: Solar cycle trends of space weather drivers
Authors: Miteva Rositsa
Published: July 2024

This report summarizes the available space weather catalogs hosted at https://catalogs.astro.bas.bg/, supported by the Institute of Astronomy and National Astronomical Observatory – Bulgarian Academy of Sciences. Namely solar flares, solar energetic protons, electron associated radio bursts and geomagnetic storms are considered. All these comprehensive records of analysed events are provided with an open access with the aim to be supported in the future. The lists cover solar cycles 23 and 24 (1996–2019) and contain the relevant parameters and their associated solar and/or interplanetary origin. The focus of this report is the solar cycle trend of solar and geomagnetic phenomena, indicating reduced productivity of either type of events in the last solar cycle and offsets with respect to the sunspot numbers.