bluuebunny/crossref_metadata_2025 huggingface dataset:
Open volume defect accumulation with irradiation in GaN, GaP, InAs, InP, Si, ZnO, and MgO
Authors: Logan J. V. , Woller K. B. , Webster P. T. , Morath C. P. , Short M. P.
Published: December 2023

Vacancies are generated in semiconductor devices while operating in the space radiation environment, impacting semiconductor carrier concentrations and dynamics. Positron annihilation lifetime spectroscopy (PALS) is used to probe these defect concentrations in bulk grown GaN, GaP, InAs, InP, Si, MgO, and ZnO both as-grown and as a function of 2–4 MeV proton irradiation. All samples were irradiated to yield a common initial damage production and characterized identically. In as-grown samples, PALS reveals vacancy concentrations above the saturation limit in the oxides, disabling further analysis. As a function of dose, of the materials in which defect accumulation could be probed, it is observed that GaN is the most resistant to the accumulation of defects (attributed to the Ga vacancies) and Si is the least. GaP (attributed to the Ga vacancy) and InAs exhibit slightly higher rates of vacancy accumulation than GaN. InP exhibits high defect accumulation rates approaching that of Si. This information is key to understanding the operation of a diverse set of semiconductors in the space radiation environment.
Reducing proton radiation vulnerability in AlGaN/GaN high electron mobility transistors with residual strain relief
Authors: Al-Mamun Nahid Sultan , Bae Joonyup , Kim Jihyun , Haque Aman , Wolfe Douglas E. , Ren Fan , Pearton Stephen J.
Published: December 2023

Strain plays an important role in the performance and reliability of AlGaN/GaN high electron mobility transistors (HEMTs). However, the impact of strain on the performance of proton irradiated GaN HEMTs is yet unknown. In this study, we investigated the effects of strain relaxation on the properties of proton irradiated AlGaN/GaN HEMTs. Controlled strain relief is achieved locally using the substrate micro-trench technique. The strain relieved devices experienced a relatively smaller increase of strain after 5 MeV proton irradiation at a fluence of 5 × 1014 cm−2 compared to the non-strain relieved devices, i.e., the pristine devices. After proton irradiation, both pristine and strain relieved devices demonstrate a reduction of drain saturation current (Ids,sat), maximum transconductance (Gm), carrier density (ns), and mobility (μn). Depending on the bias conditions the pristine devices exhibit up to 32% reduction of Ids,sat, 38% reduction of Gm, 15% reduction of ns, and 48% reduction of μn values. In contrast, the strain relieved devices show only up to 13% reduction of Ids,sat, 11% reduction of Gm, 9% reduction of ns, and 30% reduction of μn values. In addition, the locally strain relieved devices show smaller positive shift of threshold voltage compared to the pristine devices after proton irradiation. The less detrimental impact of proton irradiation on the transport properties of strain relieved devices could be attributed to reduced point defect density producing lower trap center densities, and evolution of lower operation related stresses due to lower initial residual strain.
Mueller matrix model of polarized light propagation in layered human skin in backscattering configuration
Authors: Chang Ying , Gao Wanrong
Published: December 2023

We report a two-layer Mueller matrix model of polarized light propagation through layered human skin. Our model is based on single scattering approximation and the fact that the main scatterers in the top layer are various types of cells and the scatterers beneath it consist of fibers. By modeling the first layer mainly with spherical particles inducing the characteristics represented by Mueller matrices of depolarization and diattenuation, the second layer mainly with cylindrical scatterers inducing the retardance caused by scattering and birefringence, and considering the effects of the first layer to the second one, and the equal weight of contributions from both layers to a scatterer, it is possible to separate polarization properties of the medium induced by light propagation and scattering processes. One advantage of our model is that its extension to multi-layer tissues is straightforward. Polarization effects of human nail fold are identified.
Cavitation inception noise excited by a tip leakage vortex with various gap sizes: A Eulerian–Lagrangian investigation
Authors: Ji Bin , Wang Xincheng , Bai Xiaorui , Cheng Huaiyu , Peng Xiaoxing
Published: December 2023

In this paper, the noise characteristics of tip leakage vortex cavitation (TLVC) inception are numerically investigated using a previously developed hybrid Eulerian–Lagrangian model [Wang et al., “Numerical investigation of how gap size influences tip leakage vortex cavitation inception using a Eulerian–Lagrangian method,” Phys. Fluids 35, 012113 (2023).] and the porous Ffowcs-Williams and Hawkings analogy method. A gap size significantly affects the far-field noise, which is louder for large gaps than small gaps, and for high-frequency band than low- and medium-frequency bands. Wavelet and theoretical analyses show that the main broadband noise source is the multiple collapses of cavitating bubbles and that the noise intensity is positively related to the maximum bubble radius. The maximum bubble radius depends on the unsteady pressure evolution at the TLV center, where the mean pressure is mainly influenced by the tip leakage velocity and the pressure fluctuation results from the boundary layer roll-up. This paper reveals the hydroacoustic mechanism of TLVC inception, which can provide insight into noise reduction techniques.
An active hybrid Reynolds-averaged Navier–Stokes/large eddy simulation approach for gray area mitigation
Authors: Mehta Mahitosh , Manceau Rémi , Duffal Vladimir , de Laage de Meux Benoît
Published: December 2023

During the transition from the RANS (Reynolds-Averaged Navier–Stokes) mode to the LES (Large Eddy Simulation) mode, i.e., in the so-called gray area, continuous hybrid RANS/LES approaches suffer from the well-known problem of excessively slow generation of resolved structures. Indeed, when the mesh is refined in the direction of the flow, the model is designed to reduce the modeled energy, but there is no mechanism to transfer the equivalent amount of energy into the resolved motion. Hence, the total turbulent energy and turbulent stresses are underestimated, which strongly affects the prediction of the mean flow. This also constitutes a violation of the conservation of mechanical energy, which can only be corrected by an active approach, i.e., an approach that allows the injection of resolved energy. The aim of this work is to develop such an active approach based on the introduction of a fluctuating volume force into the resolved momentum equation, similar to the anisotropic linear forcing (ALF) method proposed previously. The major difference with ALF is that the new method does not require target statistics obtained by a RANS computation but is based on a simple analysis of the rate of energy transfer related to variations in resolution, enabling the forcing to be extended to continuous hybrid RANS/LES. The application of the new method to the cases of a channel with or without periodic constriction shows a drastic improvement over the case without forcing. Although the method is applied herein to a particular hybrid RANS/LES approach (HTLES, hybrid temporal LES), it can easily be extended to any other approach, as long as a parameter identifies variations in resolution, and thus offers vast application prospects.
Single site-controlled inverted pyramidal InGaAs QD–nanocavity operating at the onset of the strong coupling regime
Authors: Huang Jiahui , Liu Wei , Cheng Xiang , Miranda Alessio , Dwir Benjamin , Rudra Alok , Kapon Eli , Wong Chee Wei
Published: December 2023

Precise positioning of single site-controlled inverted pyramidal InGaAs quantum dots (QDs) at the antinode of a GaAs photonic crystal cavity with nanometer-scale accuracy holds unique advantages compared to self-assembled QDs and offers great promise for practical on-chip photonic quantum information processing. However, the strong coupling regime in this geometry has not yet been achieved due to the low cavity Q-factor based on the (111)B-oriented membrane structures. Here, we reveal the onset of phonon-mediated coherent exciton–photon interaction on our tailored single site-controlled InGaAs QD–photonic crystal cavity. Our results present the Rabi-like oscillation of luminescence intensity between excitonic and photonic components correlated with their energy splitting pronounced at small detuning. Such Rabi-like oscillation is well reproduced by modeling the coherent exchange of the exciton-photon population. The modeling further reveals an oscillatory two-time covariance at QD-cavity resonance, which indicates that the system operates at the onset of the strong coupling regime. Moreover, by using the cavity mode as a probe of the virtual state of the QD induced by phonon scattering, it reveals an increase in phonon scattering rates near the QD–cavity resonance and asymmetric phonon emission and absorption rate of even around 50 K.
Crown morphology of oblique drop impact on a curved liquid film
Authors: Chen Weihao , Guo Yali , Chi Jun , Shen Shengqiang
Published: December 2023

The water crown deformation process of a liquid droplet oblique impacting a curved liquid film was simulated by using the coupled level-set and volume-of-fluid method. The morphological differences of the front and back sides of the water crown were compared. The jet sheet is thin and splash occurs at the front, while the crown sheet is stable and smooth at the back. The influence of impact angle on the shape of water crown is analyzed. Influence of impact angle on rear water crown height is quantified. The rim of the water crown presents an inclined line, and the variation of its inclination angle affected by the impact angle is studied. The position deviations of water crown cavities at different impact angles are investigated. With the decrease in impact angle, the spreading coefficient of the front side of the water crown cavity increases, while that of the back side decreases, and the displacement difference of the front water crown is smaller than that of the back water crown.
Investigations of spray breakup Rayleigh–Taylor instability via multiphase lattice Boltzmann flux solver
Authors: Wang Yue , Gao Shen-Yong , Zhao Fei-Yang , Yang Li-Ming , Yu Wen-Bin
Published: December 2023

Poor fuel–air mixing of the diesel spray in low ambient temperature and pressure or thin air leads to intricate fuel breakup mechanism near the nozzle, which still remains worth of study. In this study, a pressure-based modified multiphase lattice Boltzmann flux solver (MLBFS) is proposed to accommodate the fuel spray breakup characteristics of multiphase, multicomponent, and large density ratio, in which the source terms of governing equation are modified emphatically for high injection pressure. Therefore, the characteristics of microscopic diesel spray breakup induced by Rayleigh–Taylor instability are investigated, including spray penetration, spray area, and spray arc length. It is revealed that the spray penetration is increased exponentially with the fuel–air density ratio Rρ. Influenced by air resistance and circulation interference, the roll-up vortex, droplet size, and spray area increase with the decreasing of Rρ (corresponding to high ambient pressure). Affected by entrainment and Rayleigh–Taylor instability, the development of the spray arc length experienced three stages: rapid growth, peak, and violent fluctuation, in which the lower Rρ facilitates development. It is concluded that Rayleigh–Taylor instability is favorable for stimulating the spray internal circulation of spray to enhance entrainment with surrounding air, while improving roll-up and breakup in the spray tail region. Such investigation is conductive to better understanding the micro-breakup mechanisms of fuel spray in the spray-induced internal combustion engine.
Painlevé integrable property, Bäcklund transformations, Lax pair, and soliton solutions of a (3 + 1)-dimensional variable-coefficient Hirota bilinear system in a fluid
Authors: Chen Yu-Qi , Tian Bo , Shen Yuan , Zhou Tian-Yu
Published: December 2023

In this paper, we focus our attention on a (3 + 1)-dimensional variable-coefficient Hirota bilinear system in a fluid with symbolic computation. The Painlevé integrable property is derived. Via the Ablowitz–Kaup–Newell–Segur procedure, we obtain a Lax pair under the coefficient constraints. Based on the Hirota method, we obtain a bilinear form and a bilinear Bäcklund transformation under the coefficient constraints. We derive the auto-Bäcklund transformations based on the truncated Painlevé expansions. According to the bilinear form, we give the two-soliton solutions under the coefficient constraints. We also discuss the relation between the variable coefficients and soliton solutions, i.e., how the two solitons present different types with the different forms of the variable coefficients.
Enhancing turbulence modeling: Machine learning for pressure-strain correlation and uncertainty quantification in the Reynolds stress model
Authors: Sudharsun G. , Warrior Hari V.
Published: December 2023

This research study delves into the realm of enhancing the Reynolds stress model through the remarkable capabilities of machine learning. Focusing on two key aspects, we investigate the modeling of fluctuating pressure-rate-of-strain tensor and uncertainty quantification in turbulent fluid flows. In the first part of our investigation, a neural network is employed to predict the pressure-strain correlation term for the frictional Reynolds number, even in cases where it was not trained. Through the use of high-fidelity datasets, we surpass the limitations of traditional numerical methods, achieving more accurate results with reduced computational costs. Going beyond conventional analysis, we explore the isotropic and anisotropic components of the pressure-strain correlation term. Intriguingly, our findings unveil the significant influence of production and redistribution terms on the anisotropic component by 50% and viscous dissipation impacts the isotropic part by 65% in wall-bounded turbulent flows. The second part introduces a novel approach for uncertainty quantification in the Reynolds stress model. Leveraging a binary classification model, we identify error-prone points within the simulation domain with an impressive accuracy of up to 95%. This critical step paves the way for a deeper understanding of uncertainties in turbulent flows for more reliable predictions. By harnessing the power of machine learning, our study provides two compelling ways to enhance the Reynolds stress model, contributing to a more efficient and dependable prediction of turbulent fluid dynamics.
Fluid–structure interaction on vibrating square prisms considering interference effects
Authors: Chen Zengshun , Wang Yatai , Wang Siyu , Huang Hailin , Yuan Kuiwen , Li Sijia , Li Cruz Y. , Xu Yemeng
Published: December 2023

Existing research on interference effects predominantly focuses on rigid structures. However, studies based on rigid models tend to overlook the feedback of structural motions on the flow field, thus failing to capture the intrinsic dynamics of the interference effect induced by wind-induced structural vibrations. This paper provides a comprehensive analysis of the fluid–structure interaction mechanisms considering interference effects involving two parallel square prisms, employing large-eddy simulation (LES). Various factors, including wind speed, arrangement, and vibration amplitude, are meticulously considered in the analysis. The study utilized three-dimensional LES simulations, incorporating the narrowband synthesis random flow generator method for inlet turbulence generation and adjusted through the “feedback” approach to ensure accuracy and efficiency. The research highlighted different structural arrangements exhibited distinct interference effects, and the end effect of the structure could substantially modify the flow pattern at various heights. In the tandem arrangements, the study observed several flow phenomena, including early reattachment, attenuation of the end effect, premature formation of roll structures, increased turbulence in the flow field due to vibration, resulting in wider second leading-edge separation, and a fragmented wake flow on the downstream structure. For side-by-side arrangements, the “acceleration effect” was identified and found to be further intensified by structural vibrations. The vibration of the interfering structure was noted to cause changes in vortex shedding frequencies and alterations in the wake flow pattern. In addition, vibration would enhance the interference effect but increasing amplitude and wind speed might diminish the interference effect. Overall, this study offers valuable insight into the intricate interplay of factors influencing the aerodynamics of parallel structures across diverse arrangements and under varying conditions.
Occupational and environmental factors influencing morale of United States federal wildland firefighters
Authors: Granberg Rachel M. , Shen Ting , Pearson Seth W. , Verble Robin M.
Published: December 2023

Background Wildland firefighters have physically and psychologically demanding jobs that can result in social, economic and health-related stress. Previous studies have examined the physiological and physical effects of a career in wildland fire, but fewer studies have addressed psychological effects, and to date, none have directly analysed the hiring and work experiences of wildland firefighters. Aims We surveyed work experiences, health and well-being, and morale of wildland firefighters, explored factors that can improve recruitment and retention, and summarised broad patterns. Methods We conducted a voluntary anonymous survey of 708 federal wildland firefighters via an online platform over 2 months in 2022. Key results Respondents reported dissatisfaction with recruitment and hiring processes, low base salaries, poor mental health outcomes, and health and safety concerns. Respondents also reported the high importance of training, performance feedback and work environment to their retention in the field. We found significant effects of wildland firefighting on family status. Conclusions Wildland firefighters report experiencing low morale, financial stress, personal life strain and poor mental health outcomes. Implications These data provide a framework to establish future policy and research priorities and highlight the need for organisational actions and change.
Infants’ understanding of the causal power of agents and tools
Authors: Adibpour Parvaneh , Hochmann Jean-Rémy
Published: December 2023

Tools are objects that are manipulated by agents with the intention to cause an effect in the world. We show that the cognitive capacity to understand tools is present in young infants, even if these tools produce arbitrary, causally opaque effects. In experiments 1–2, we used pupillometry to show that 8-mo-old infants infer an invisible causal contact to account for the—otherwise unexplained—motion of a ball. In experiments 3, we probed 8-mo-old infants’ account of a state change event (flickering of a cube) that lies outside of the explanatory power of intuitive physics. Infants repeatedly watched an intentional agent launch a ball behind an occluder. After a short delay, a cube, positioned at the other end of the occluder began flickering. Rare unoccluded events served to probe infants’ representation of what happened behind the occluder. Infants exhibited larger pupil dilation, signaling more surprise, when the ball stopped before touching the cube, than when it contacted the cube, suggesting that infants inferred that the cause of the state change was contact between the ball and the cube. This effect was canceled in experiment 4, when an inanimate sphere replaced the intentional agent. Altogether, results suggest that, in the infants’ eyes, a ball (an inanimate object) has the power to cause an arbitrary state change, but only if it inherits this power from an intentional agent. Eight-month-olds are thus capable of representing complex event structures, involving an intentional agent causing a change with a tool.
First and second language speakers’ sensitivity to the distributional properties of
wh-clauses
Authors: Domazetoska Ivana , Zhao Helen
Published: December 2023

The present study investigates L1 and L2 English speakers’ knowledge of the wh-clausal
construction along the parameters of (a) conventionality, distinguishing between high-frequency conventional and low-frequency
unconventional formulations (I asked him why they agreed/why did they agree), and (b) proposition type,
differentiating between interrogative versus non-interrogative proposition types (I asked / told him why they
agreed). We also consider the extent to which L2 speakers’ constructional knowledge is influenced by learners’ target
language experience, such as L2 proficiency, context of L2 learning (ESL or EFL), and target language exposure. Results from a
judgment task revealed nuances in L1-L2 discriminatory capacities, and more importantly, differences in sensitivity to proposition
type between the ESL and EFL group, but no L2 differences in sensitivity to conventionality. L2 proficiency, speakers’ length of
target immersion experience, and classroom exposure were shown to also impact linguistic sensitivity, highlighting a moderating
effect of target language exposure and an important role for classroom instruction.
Laser frequency stabilization with the use of homodyne quadrature interferometers
Authors: Di Fronzo C , Holland N A , Mitchell A L , Cooper S J , Valentini M , Martynov D , Prokhorov L , Mow-Lowry C M
Published: December 2023

Laser frequency stabilization is a crucial technique for precision metrology. We demonstrate laser frequency control using a compact, interferometric sensor, specially modified for sensitivity to laser frequency noise. This setup achieves a balance between compact size, ease of use, and affordability. We stabilize the laser frequency noise, of a low-cost solid-state laser, to 4.5 

k
H
z

 

H
z

−
1

at 1 Hz. The requirement for additional technology, and expense, is negated when identical, compact, interferometric sensors are deployed. The use of compact interferometric sensors is already a technology under investigation for integration into gravitational-wave observatories and out study enables wider applications by mitigating a fundamental noise source, inherent to their design.
Metasurface-based bandwidth and isolation enhancement for compact H-plane coupled antennas
Authors: Wei Xin , Wang Guangming , Wang Yawei , Zou Xiaojun , Tian Chao , Bai Hao , Yu Zhongwu , Cai Tong
Published: December 2023

A simple metasurface (MS) composed of a square metal ring and four extended metal strips is designed to simultaneously enhance the bandwidth and isolation of H-plane coupled microstrip patch antenna array in this paper. By adding the MS above the patch array, a new resonance is formed to increase the working bandwidth and the coupling between the antenna array is largely depressed to enhance the isolation property. An antenna array with MS is simulated, fabricated and measured. The simulated and measured results are in good agreements. Measured results indicate that the bandwidth with S
11 ⩽ −10 dB is broadened by 8.1% compared with the original coupled antennas. In addition, within the working band, the isolation level is better than −20 dB, and the maximum mutual coupling reduction reaches 39.6 dB at 5.19 GHz, performing an excellent wideband decoupling effect. Moreover, the proposed method has been extended to large antenna arrays, implying that it can be widely used in multiple-input multiple-output or the wireless Rx/Tx system.
Dielectric performance improvement of polypropylene film modified by γ-ray irradiation for HVDC capacitors
Authors: Xiao Meng , Wang Kaixu , Song Yuning , Du Boxue
Published: December 2023

Polypropylene (PP) films exhibit low dielectric strength and high losses under elevated temperatures and strong electric field environments. This paper proposes a method to improve the dielectric properties based on γ-ray irradiation crosslinking, investigates the effect of the type of sensitizer on the crosslinking reaction, and explores the effect of crosslinking structure on the dielectric properties of PP films such as breakdown strength. The results showed that the type of group in the sensitizer influenced its activity in the crosslinking reaction, and the modified films added with pentaerythritol triacrylate (PETA) exhibited the highest crosslinking degree of 25.68%. In addition, it was found that the crosslinked structure improved the stability of the molecular chains at high temperatures and reduced the probability of thermal breakdown. At 115 °C, the modified films with PETA showed a 72.5% reduction in conductivity and a 33.6% increase in breakdown strength. This method demonstrates the importance of irradiation crosslinking modification for improving the reliability of PP films in high-temperature and strong electric field applications.
Room-temperature ferromagnetic CoSe2 nanoplates synthesized by chemical vapor deposition
Authors: Tian Sen , Wang Wenjie , Zhao Mengfan , Han Yilin , Tian Yuxin , Ji Shengxiang , Yao Liang , Liu Lixuan , Ling Feifei , Jia Zhiyan , Zhang Fang
Published: December 2023

Among novel two-dimensional materials, transition metal dichalcogenides (TMDs) with 3d magnetic elements have been extensively researched owing to their unique magnetic, electric, and photoelectric properties. As an important member of TMDs, CoSe2 is an interesting material with controversial magnetic properties, hitherto there are few reports related to the magnetism of CoSe2 materials. Here, we report the synthesis of CoSe2 nanoplates on Al2O3 substrates by chemical vapor deposition (CVD). The CVD-grown CoSe2 nanoplates exhibit three typical morphologies (regular hexagonal, hexagonal, and pentagonal shapes) and their lateral sizes and thickness of CoSe2 nanoplates can reach up to hundreds of microns and several hundred nanometers, respectively. The electric-transport measurement shows a metallic feature of CoSe2 nanoplates. Furthermore, the slanted hysteresis loop and nonzero remnant magnetization of the CoSe2 nanoplates confirm the ferromagnetism in the temperature range of 5–400 K. This work provides a novel platform for designing CoSe2-based spintronic devices and studying related magnetic mechanisms.
Andreev reflection in graphene nanoribbons induced by d-wave superconductors
Authors: Takagaki Y
Published: December 2023

Honeycomb and square lattices are combined as a tight-binding model to examine the Andreev reflection in graphene nanoribbons induced by a superconductor. The superconducting symmetry is assumed to be the d-wave. The zero-bias tunneling conductance peak, which is generally produced by the d-wave superconductor, is absent for the nanoribbons under conditions similar to those when a quantum wire is the normal conductor. For the anisotropic superconductivity, propagating modes appear in the superconductor even for biases below the top of the superconducting energy gap. Features appear in the conductance at the subgap population thresholds of these propagating modes as a finite-size effect of the lattice system. The surface Andreev bound states responsible for the zero-bias anomaly also cause transport resonances in the vicinity of the zero bias despite the aforementioned destruction of the anomaly. The conductance spectra revealing these excitation behaviors are fairly unchanged regardless of the presence of a hopping barrier at the interface with the superconductor. The insensitivity to the interface scattering highlights the fact that barrier-less situation cannot be realized for the model due to the heterogeneous lattice. Concerning specular Andreev reflection, the wavefunction parity gives rise to its blocking for single-mode zigzag-edged nanoribbons. The blocking is suppressed when the anisotropic superconductivity is asymmetric for the nanoribbons.
A miniaturized spot-focusing microwave sensor for broad-band reflectivity measurements
Authors: Fang Yang , Hui Peilin , Chen Zhenmao , Li Yong , Xie Shejuan , Chen Hongen
Published: December 2023

This study presents a novel spot-focusing microwave sensor designed for on-site monitoring of absorbing materials and coatings, a critical process in assessing the performance of equipment in service. The sensor addresses the challenge of integrating miniaturization, wide bandwidth, and focused radiation-requirements that are typically at odds in microwave sensor design. The developed approach utilizing a multi-layer lens nesting structure to achieve narrow-beam radiation over an ultra-wideband (UWB) frequency range. Each layer of the lens system is engineered to concentrate beams within specific frequency bands, enabling consistent performance across a broad spectrum. In addition, we introduce a composite feeding structure characterized by exponential gradient slots that enhance UWB performance while minimizing cross-polarization effects. The sensor demonstrates exceptional capabilities, achieving over 8 dB of radiation gain and maintaining a voltage standing wave ratio (VSWR) under 2.5 within a 2–22 GHz frequency band. Its compact size (95 mm in diameter and 75 mm in height) does not compromise its ability to emit a Gaussian beam with a narrow radiation pattern of less than ±30°, simulating plane-wave characteristics essential for near-field on-site measuring. Accompanying the sensor is a novel on-site reflectivity measuring method that leverages time-domain gating technology to mitigate interference signal impact. Measurement results validate the sensor and method’s precision, with an average error margin of 0.78 dB. This breakthrough in sensor design and methodology marks a significant advancement in the on-site evaluation of absorbing materials and coatings.
A wave energy driven high-performance self-powered oil spill positioner
Authors: Li Zhaozhao , Chen Li , Zhang Bin , Jiang Xin , Zhang Jinnan , Zhang Shibo
Published: December 2023

The oil spill positioner is capable of real-time monitoring oil films on the sea surface. However, the lack of high-performance power supply methods greatly restricts the application of oil spill positioner. In this research, we design a high-performance self-powered oil spill positioner based on a soft-contact-triboelectric-nanogenerator (SC-TENG). This device achieves soft-contact by attaching rabbit fur to the rotor, which can effectively reduce frictional resistance, quickly transfer charge to the electrode, and improve the durability of the parts. First, we calculate the highest occupied molecular orbital and the lowest unoccupied molecular orbital of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) molecules through first-principles simulations, and compared the ease of electron excitation between the two materials. The results show that the performance of SC-TENG with PVDF as dielectric material is significantly better than that of PTFE. At the same time, this phenomenon has been confirmed by experiments. On the basis of experimental and simulate research on two types of power management circuits, a bridge rectifier circuit with the function of converting alternating current to direct current is selected to realize the self-power supply of the oil spill positioner. Additionally, by optimizing the structure of the SC-TENG and employing a bridge rectifier circuit, the SC-TENG can achieve a maximum open-circuit voltage of 1400 V and a short-circuit current of 3.49 μA, which are enough to light up 200 light-emitting diodes and power the oil spill positioner. Finally, we simulate the open-circuit voltage and short-circuit current of the SC-TENG on a six-degree-of-freedom platform and test its durability under real-world ocean wave conditions, all of which show excellent performance. This work develops an efficient wave energy conversion mechanism and successfully realizes the high-performance self-powering of the oil spill positioner, making oil spill monitoring more flexible and reliable.
Ferromagnetic insulating substrate for magnetic proximity studies: LaCoO3 thin film
Authors: Lee Yeonjae , Kim Youngdo , Lee Sangjae , Kim Changyoung
Published: December 2023

Ferromagnetic insulators (FMIs) are intriguing not only due to their rare nature, but also due to their potential applications in spintronics and various electronic devices. One of its key promising applications is based on an FMI-induced magnetic proximity effect, which can impose an effective time-reversal symmetry breaking on the target ultrathin layer to realize novel emergent phenomena. Here, we conduct systematic studies on thin film LaCoO3, an insulator known to be ferromagnet under tensile strain, with varying thicknesses, to establish it as an FMI platform to be integrated in heterostructures. The optimal thickness of the LaCoO3 layer, providing a smooth surface and robust ferromagnetism with large remanence, is determined. A heterostructure consisting of an ultrathin target layer (2 uc SrRuO3), the LaCoO3 FMI layer, and the La0.5Sr0.5CoO3 conducting layer has been fabricated and the angle-resolved photoemission spectroscopy measurement on the multi-layer system demonstrates a sharp Fermi edge and a well-defined Fermi surface without the charging effect. This demonstrates the feasibility of the proposed heterostructure using LaCoO3 thin film as the FMI layer, and further lays a groundwork to investigate the magnetic proximity induced phases in quantum materials.
Facile synthesis of β-Ga2O3 based high-performance electronic devices via direct oxidation of solution-processed transition metal dichalcogenides
Authors: Feria Denice Navat , Huang Qi-Zhi , Yeh Chun-Shao , Lin Shi-Xian , Lin Der-Yuh , Tseng Bo-Chang , Lian Jan-Tian , Lin Tai-Yuan
Published: December 2023

Gallium oxide (Ga2O3) is a promising wide bandgap semiconductor that is viewed as a contender for the next generation of high-power electronics due to its high theoretical breakdown electric field and large Baliga’s figure of merit. Here, we report a facile route of synthesizing β-Ga2O3 via direct oxidation conversion using solution-processed two-dimensional (2D) GaS semiconducting nanomaterial. Higher order of crystallinity in x-ray diffraction patterns and full surface coverage formation in scanning electron microscopy images after annealing were achieved. A direct and wide bandgap of 5 eV was calculated, and the synthesized β-Ga2O3 was fabricated as thin film transistors (TFT). The β-Ga2O3 TFT fabricated exhibits remarkable electron mobility (1.28 cm2 Vs−1) and a good current ratio (I
on/I
off) of 2.06 × 105. To further boost the electrical performance and solve the structural imperfections resulting from the exfoliation process of the 2D nanoflakes, we also introduced and doped graphene in β-Ga2O3 TFT devices, increasing the electrical device mobility by ∼8-fold and thereby promoting percolation pathways for the charge transport. We found that electron mobility and conductivity increase directly with the graphene doping concentration. From these results, it can be proved that the β-Ga2O3 networks have excellent carrier transport properties. The facile and convenient synthesis method successfully developed in this paper makes an outstanding contribution to applying 2D oxide materials in different and emerging optoelectronic applications.
Electrical, thermal and noise properties of platinum-carbon free-standing nanowires designed as nanoscale resistive thermal devices
Authors: Piasecki Tomasz , Kwoka Krzysztof , Gacka Ewelina , Kunicki Piotr , Gotszalk Teodor
Published: December 2023

Platinum-carbon (PtC) composite nanowires were fabricated using focused electron beam induced deposition and postprocessed, and their performance as a nanoscale resistive thermal device (RTD) was evaluated. Nanowires were free-standing and deposited on a dedicated substrate to eliminate the influence of the substrate itself and of the halo effect on the results. The PtC free-standing nanowires were postprocessed to lower their electrical resistance using electron beam irradiation and thermal annealing using Joule heat both separately and combined. Postprocessed PtC free-standing nanowires were characterized to evaluate their noise figure (NF) and thermal coefficients at the temperature range from 30 K to 80 °C. The thermal sensitivity of RTD was lowered with the reduced resistance but simultaneously the NF improved, especially with electron-beam irradiation. The temperature measurement resolution achievable with the PtC free-standing nanowires was 0.1 K in 1 kHz bandwidth.
Intensity-modulated proton and carbon-ion radiotherapy using a fixed-beam system for locally advanced lung cancer: dosimetric comparison with x-ray radiotherapy and normal tissue complication probability (NTCP) evaluation
Authors: Ming Xue , Mao Jingfang , Ma Ningyi , Chen Jian , Wang Weiwei , Sheng Yinxiangzi , Wu Kailiang
Published: December 2023

Objective. To assess the dosimetric consequences and the normal tissue complication probability (NTCP) for the organs at risk (OARs) in intensity-modulated particle radiotherapy of proton (IMPT) and carbon-ion (IMCT) using a fixed-beam delivery system when compared with intensity-modulated photon radiotherapy (IMRT) for locally advanced small-cell lung cancer. Approach. The plans were all designed under the same total relative biological effectiveness (RBE)-weighted prescription dose, in which the planning target volume (PTV) of the internal gross target volume(IGTV) and the PTV of the clinical target volume was irradiated with 69.3 Gy (RBE) and 63 Gy (RBE), respectively, using a simultaneously integrated boosting (SIB) technique. NTCPs were estimated for heart, lung, esophagus and spinal cord by Lyman–Kutcher–Burman (LKB) and logistic models. Dose escalation was simulated under the desired NTCP values (0.05, 0.10 and 0.50) of the three radiation techniques. Main results. Under the similar target coverage, almost all OARs were significantly better spared (p < 0.05) when using the particle radiotherapy except for D1cc (the dose to 1 cm3 of the volume) of the proximal bronchial tree (p > 0.05). At least 57.6% of mean heart dose, 28.8% of mean lung dose and 19.1% of mean esophageal dose were reduced compared with IMRT. The mean NTCP of radiation-induced pneumonitis (RP) in the ipsilateral lung was 0.39 ± 0.33 (0.39 ± 0.31) in IMPT plans and 0.36 ± 0.32 (0.35 ± 0.30) in IMCT plans compared with 0.66 ± 0.30 (0.64 ± 0.28) in IMRT plans by LKB (logistic) models. The target dose could be escalated to 78.3/76.9 Gy (RBE) in IMPT/IMCT plans compared with 61.7 Gy (RBE) in IMRT plans when 0.50 of NTCP in terms of RP in the ipsilateral lung was applied. Significance. This study presents the potential of better control of the side effects and improvement of local control originating from the dosimetric advantage with the application of IMPT and IMCT with the SIB technique for locally advanced lung cancer, even with limited beam directions.
Single-pulse electrical stimulation artifact removal using the novel matching pursuit-based artifact reconstruction and removal method (MPARRM)
Authors: Xie Tao , Foutz Thomas J , Adamek Markus , Swift James R , Inman Cory S , Manns Joseph R , Leuthardt Eric C , Willie Jon T , Brunner Peter
Published: December 2023

Objective. Single-pulse electrical stimulation (SPES) has been widely used to probe effective connectivity. However, analysis of the neural response is often confounded by stimulation artifacts. We developed a novel matching pursuit-based artifact reconstruction and removal method (MPARRM) capable of removing artifacts from stimulation-artifact-affected electrophysiological signals. Approach. To validate MPARRM across a wide range of potential stimulation artifact types, we performed a bench-top experiment in which we suspended electrodes in a saline solution to generate 110 types of real-world stimulation artifacts. We then added the generated stimulation artifacts to ground truth signals (stereoelectroencephalography signals from nine human subjects recorded during a receptive speech task), applied MPARRM to the combined signal, and compared the resultant denoised signal with the ground truth signal. We further applied MPARRM to artifact-affected neural signals recorded from the hippocampus while performing SPES on the ipsilateral basolateral amygdala in nine human subjects. Main results. MPARRM could remove stimulation artifacts without introducing spectral leakage or temporal spread. It accommodated variable stimulation parameters and recovered the early response to SPES within a wide range of frequency bands. Specifically, in the early response period (5–10 ms following stimulation onset), we found that the broadband gamma power (70–170 Hz) of the denoised signal was highly correlated with the ground truth signal (

R
=
0.98
±
0.02

, Pearson), and the broadband gamma activity of the denoised signal faithfully revealed the responses to the auditory stimuli within the ground truth signal with

94
%
±
1.47
%

sensitivity and

99
%
±
1.01
%

specificity. We further found that MPARRM could reveal the expected temporal progression of broadband gamma activity along the anterior-posterior axis of the hippocampus in response to the ipsilateral amygdala stimulation. Significance. MPARRM could faithfully remove SPES artifacts without confounding the electrophysiological signal components, especially during the early-response period. This method can facilitate the understanding of the neural response mechanisms of SPES.
Gradient Gibbs measures with periodic boundary laws of a generalized SOS model on a Cayley tree
Authors: Haydarov F H , Ilyasova R A
Published: December 2023

We consider gradient Gibbs measures corresponding to a periodic boundary law for a generalized solid-on-solid (SOS) model with spin values from a countable set on a Cayley tree. On the Cayley tree, detailed information on gradient Gibbs measures for models of SOS type is given in Botirov and Haydarov (2020 J. Stat. Mech. 093102), Henning et al (2019 Electron. J. Probab.
24 104), Haydarov and Rozikov (2022 Rep. Math. Phys.
90 81–101) and Kulske and Schriever (2017 Markov Process. Relat. Fields
23 553–90). We continue this work for the generalized SOS model. Namely, in this paper, the problem of finding gradient Gibbs measures which correspond to periodic boundary laws is reduced to a functional equation and, by solving this equation, all gradient Gibbs measures with four periodic boundary laws are found.
PCM-based domestic solar water heating in Malaysia: Setbacks and countermeasures
Authors: Fadzlin Wan Afin , Hasanuzzaman Md. , Rahim Nasrudin Abd
Published: December 2023

Solar water heating (SWH) systems have yet to be widely employed despite their promising features for hot water production, especially in rural areas. This paper discusses several setbacks to the implementation of SWH systems. Generally, the setbacks are related to weather issues, the collector’s technical damages, and financial constraints. A few potential countermeasures to these setbacks are also listed.
Investigation of Thermal Performance and Chemical Stability of Metal Infused Salt Hydrate Phase Change Material for Thermal Energy Storage
Authors: Pandey AK , Reji Kumar R , Samykano M , Buddhi D , Tyagi VV
Published: December 2023

Thermal energy storage (TES) is a technique that is considered a very desirable technology with a high potential to overcome the gap between demand and supply. Phase change materials (PCMs) are considered to be a highly favourable thermal energy storage materials. Besides that, PCM has certain drawbacks, such as lower thermal conductivity and higher light transmission; owing to this, the heat transfer rate and energy storage density are less. The performance of the PCMs can be improved by adding highly conductive nanoparticles. In this study, various weight percentages (0.1% - 5.0%) of Copper (II) oxide nanoparticles are dispersed with salt hydrate phase change materials with melting temperature 50 °C and investigated the thermal and chemical properties using Thermogravimetric analyzer, thermal conductivity analyzer, and Fourier transform infrared spectrum. Results shows that the prepared nanocomposites have chemically and thermally stable up to 467 °C. The thermal conductivity was increased by 62.64%, at 3.0 wt% Copper (II) oxide with salt hydrate PCM. The developed nanocomposites have better thermophysical properties than pure salt hydrate, which may be applied for TES applications like solar water heating, photovoltaic thermal systems, and electronic cooling systems.
Effect of lead sintering aid to TiO2 photoanode for flexible dye sensitized solar cell
Authors: Khir H , Pandey A K , Saidur R , Ahmad M S , Dewika M , Samykano M
Published: December 2023

The commercial application of flexible dye sensitized solar cells (DSSCs) is somewhat limited due to the devices’ low conversion efficiency. The low sintering temperature in preparing the photoanode has caused poor interparticle contact, low charge transfer and low efficiency. Hence, this research aims to improve the interparticle contact of titanium dioxide (TiO2) photoanode with the novel use of lead (Pb) nanoparticles as sintering aid at low temperature. TiO2-Pb composite photoanode was prepared with different composition of Pb including 4% and 7% sintered at low temperature of 250°C. The research discovered that TiO2 photoanode mixed with 4% Pb composition showed the lowest charge transfer resistance (RCT) even at low sintering temperature. The RCT value was even lower than a commercial TiO2 photoanode sample that was sintered at 450°C. The addition of Pb sintering aid has improved interparticle contact in the photoanode via the neck formation at the TiO2-Pb interface and enhanced charge transfer despite the low temperature. The prepared photoanode samples displayed potential in developing highly efficient flexible DSSC.
Recycling End-of-Life Photovoltaic Modules in Malaysia: Challenges and Potential Solutions
Authors: Yu Hui Fang , Hasanuzzaman Md , Rahim Nasrudin Abd
Published: December 2023

As evidenced from recent policies encouraging renewable energy (RE) penetration in Malaysia, it is envisioned that solar photovoltaic (PV) in the country will receive a significant boost in growth as well. The proliferation of solar PV systems is viewed as a great leap in assisting the decarbonization of our energy generation systems, yet concerns have been raised on the sustainable management of the emerging waste PV modules. Currently, the common treatment methods for the majority of end-of-life (EoL) PV modules in many countries including Malaysia, are landfill disposal or bulk recycling in pre-existing recycling facilities. Even though these methods are simpler in operation due to minimal efforts required to sustainably manage these EoL modules, there is a high probability for environmental issues to occur including leakage of toxic materials and loss of valuable resources. As a result, high-value closed-loop recycling has been proposed to remediate these detrimental effects, but its execution could introduce challenges in Malaysia which this paper attempts to examine upon. Consequently, recommendations to alleviate the challenges faced are proposed, along with potential trade-offs that may arise from the solutions suggested. In essence, research and development (R&D), support from the authorities, as well as cooperation between governmental and private organisations, are necessary in establishing a sustainable and holistic framework for managing PV waste in Malaysia.