bluuebunny/crossref_metadata_2025 huggingface dataset:
New insights in the stratification of an argon positive column plasma. I. Theory
Authors: Boeuf J. P. , Boufendi L. , Dosbolayev M. K. , Orazbayev S. A. , Ramazanov T. S.
Published: July 2024

This study investigates the conditions leading to stratification in a quasineutral argon positive column plasma, focusing on a pressure-column radius product, pR, in the range 0.1–10 Torr cm neglecting Coulomb collisions and electron–ion recombination. We achieve this by linearizing the electron transport equations while incorporating metastable ionization. Dispersion relations indicate that positive column stratification may result from a thermoelectric transport term in the electron energy equation, particularly the density gradient term in the energy flux related to the Dufour effect, or from the non-linearity of ionization due to metastable ionization. The present study shows that for small values of the pR product (less than about 0.3–0.5 Torr cm), the plasma is maintained by direct ionization and the stratification of the positive column is entirely due to the thermoelectric term of the electron energy equation. For larger pR products, the reduced electric field decreases due to lower charged particle losses to the wall, and the plasma is maintained by stepwise and associative ionization of metastable atoms. The dispersion relations show that the growth of instabilities above 0.3–0.5 Torr cm is still linked to the thermoelectric coefficient but that the presence of metastable atoms is necessary for the development of instabilities. The non-linearity of the metastable density with the electron density is not the cause of the stratification in this range of pR product, contrary to previous claims. Experiments and particle simulations presented in Paper II [Dosbolayev et al., Phys. Plasmas 13, 085015 (2024)] are qualitatively consistent with the theory presented in this article.
Effect of coal moisture content on gas desorption and diffusion: A theoretical model and numerical solution
Authors: Wang Gang , Han Zongxiang , Xu Hao , Peng Shoujian , Huang Qiming , Long Qingming
Published: July 2024

Moisture in coal plays a critical role in influencing gas desorption. This work numerically establishes a mathematical model for the gas desorption in spherical coal particles with different moisture contents based on the free gas density gradient (FGDG) concept. Importantly, the gas desorption pressure drop starting time (DPDST) was defined, and its response mechanism to moisture content was explored. Finally, the theoretical differences between the classical Fick's and FGDG models in describing the gas desorption/diffusion of water-containing coal were discussed in particular. The results show that the final stabilized dimensionless gas pressure in coal becomes closer and closer to the external initial dimensionless pressure as the coal moisture content increases. The DPDST is inversely proportional to the moisture content of the coal sample, possibly because more gas adsorption sites are occupied by water molecules at high moisture contents. Three different well-used empirical formulas for gas desorption were used for fitting, with one of the nth power of time t empirical formulas yielding the best fit. Based on the fitting results, the gas desorption amount limit is inversely proportional, and the gas desorption rate is proportional to the moisture content of the coal sample. On the basis of the diffusion coefficient inversion results, the prediction accuracy of the FGDG model is higher than that of the Fick's model. Theoretically, the diffusion coefficients of both models are inversely proportional to the coal moisture content, possibly because water molecules may occupy the adsorption sites of gas molecules and hinder the diffusion channel.
Chiral metasurface device in near-infrared region designed by rectangular arrays
Authors: Jiao Wensheng , Ren Yuqing , Peng Hsin-Han , Liu Kaizhu , Wang Chao , Li Rui , Chui Hsiang-Chen
Published: July 2024

Polarization is one of the fundamental properties of light and has an important application value, involving multiple fields, such as imaging, display, quantum computing, and biosensing. The artificial metasurface can achieve comprehensive control of electromagnetic waves, such as amplitudes, phases, and polarization states. Compared to traditional optical devices, the metasurfaces have advantages, such as small size and diverse functions, meeting the needs of modern optical systems for ultra-lightweight, ultra-compact, and multifunctional optical components. Chiral media are widely presented in various macroscopic and microscopic systems in nature. Circular dichroism (CD) is commonly used to describe the difference in absorption rates of left-handed circularly polarized light and right-handed circularly polarized light in chiral media. However, the optical response of chiral media in nature is usually weak and mainly located in the ultraviolet band, which limits their detection sensitivity and practical application range. In this work, we proposed a chiral metasurface model with four rectangular holes with proper rotation. By rotating the rectangular or elliptical holes at a certain angle, the symmetry of the structure is disrupted, making it chiral. The proposed metasurface devices were fabricated, and the optical measurements were performed, which were in good agreement with the designs. The normalized CD values are around 0.01 at the near-infrared region. This work provides a complete procedure of the metasurface device and initials chiral-tunable flat meta-devices. It also has broad application prospects in fields, such as polarization imaging, life sciences, and drug chiral detection.
On the dynamics of nonlinear Rossby solitary waves via the Ostrovsky hierarchy
Authors: Zhang Zhihui , Zhang Ruigang , Yang Liangui , Liu Quansheng
Published: July 2024

The impact mechanisms of large-scale atmospheric and ocean dynamics on weather and climate change have long been a focus of attention. In this paper, based on the generalized β-plane approximation with turbulence dissipation and forcing terms, we derived the Ostrovsky equation describing the evolution of Rossby wave amplitudes using multiscale and perturbation expansion methods. This is the first derivation of the Ostrovsky equation from the quasi-geostrophic potential vorticity conservation equation. A detailed analysis was conducted on the evolution of Rossby waves under the influence of multiple physical factors. We investigated the evolution of flow fields and Rossby wave amplitudes under conditions of weak shear in the background flow and discussed the effects of physical factors such as Rossby parameter β0 and turbulence dissipation on the evolution of dipole blocking and Rossby wave amplitudes. The results indicate that an increase in the Rossby parameter slows down the evolution of dipole blocking and amplitudes, while an increase in turbulence dissipation and background flow shear accelerates these evolutions. Additionally, we conducted comparative analyses on the evolution of relative vorticity and perturbed relative vorticity, further enriching the theoretical achievements in atmospheric dynamics.
Relations between normal state nonreciprocal transport and the superconducting diode effect in the trivial and topological phases
Authors: Angehrn Georg , Legg Henry F. , Loss Daniel , Klinovaja Jelena
Published: July 2024

Nonreciprocal transport effects can occur in the normal state of conductors and in superconductors when both inversion and time-reversal symmetry are broken. Here, we consider systems where magnetochiral anisotropy of the energy spectrum due to an externally applied magnetic field results in a rectification effect in the normal state and a superconducting (SC) diode effect when the system is proximitized by a superconductor. Focusing on nanowire systems, we obtain analytic expressions for both normal state rectification and SC diode effects that reveal the commonalities—as well as differences—between these two phenomena. Furthermore, we consider the nanowire brought into an (almost) helical state in the normal phase or a topological SC phase when proximitized. In both cases, this reveals that the topology of the system considerably modifies its nonreciprocal transport properties. Our results provide insights into how to determine the origin of nonreciprocal effects and further evince the strong connection of nonreciprocal transport with the topological properties of a system.
Stress relaxation following sudden cessation of steady shearing from polymer rotarance theory
Authors: Pak Myong Chol , Giacomin A. J. , Kanso M. A.
Published: July 2024

Deriving rheological material functions from rotarance theory proceeds in two steps. We first solve the general diffusion equation to get the polymer orientation distribution, then we integrate the result in phase space to get the material functions. Rotarance theory thus relies entirely on polymer orientation to explain the elasticity of a polymeric liquid and, thus, to explain how such complex fluids depart from Newtonian behavior. We are attracted to rotarance theory by virtue of its versatility. The rheological behavior can be deduced, from first principles, from the structure of the macromolecule. However, of the 13 canonical rheological material functions, 5 are still unknown. We devote this paper to stress relaxation following cessation of steady shear flow. We arrive at analytical expressions for the relaxation of the orientation distribution function and then integrate this to get expressions for the relaxation of the shear stress, along with both normal stress differences.
Dopants and oxygen vacancy migration mechanism in temperature-stable (Ba, Ca)TiO3-based ceramics
Authors: Cheng Xu , Zhen YiChao , Zhao Peiyao , Hui Kezhen , Zhang Weichen , Jiang Ying , Guo Limin , Fu Zhenxiao , Cao Xiuhua , Wang Xiaohui
Published: July 2024

The migration of dopants and oxygen vacancy (VO) significantly affect the temperature stability and insulation degradation behavior of BaTiO3-based dielectric ceramics. In this work, the improved dielectric properties and reliability are achieved in (Ba, Ca)TiO3 (BCT)-based ceramics due to the intriguing effect of Ca substitution. Theoretical calculations and experiments reveal the underlying mechanisms in the migration of dopants and VO. The migration barrier of dopants is increased by ∼0.02 eV or less due to the lattice shrinkage, while it is decreased by ∼0.5 eV due to the interatomic space expansion effect caused by the small size of Ca. Thus, the core–shell structure is more susceptible in BCT-based ceramics with higher Ca content. The VO is confirmed to be more stable near the Ca ion, forming the [CaBa-VO]·· defect complex. However, the migration barrier is significantly decreased among the first nearest O sites of Ca due to the enlarged space near Ca ion. Thus, the activation energy of VO and insulation degradation behavior are improved in BCT-based ceramics with moderate Ca content but deteriorate with high content, in which the intragranular migration channels with the low barrier are formed. The present results reveal the significant effect of Ca substitution on the migration of dopants and VOs, and further on the dielectric temperature stability and reliability.
Pre-asymptotic analysis of Lévy flights
Authors: Araújo H. A. , Pagnini G.
Published: July 2024

We study the properties of Lévy flights with index 0<α<2 at elapsed times smaller than those required for reaching the diffusive limit, and we focus on the bulk of the walkers’ distribution rather than on its tails. On the basis of the analogs of the Kramers–Moyal expansion and of the Pawula theorem, we show that, for any α≤2/3, the bulk of the walkers’ distribution occurs at wave-numbers greater than (2/α)1/(2α)≥1, and it remains non-self-similar for a time-scale longer than the Markovian time-lag of at least one order of magnitude. This result highlights the fact that for Lévy flights, the Markovianity time-lag is not the only time-scale of the process and indeed another and longer time-scale controls the transition to the familiar power-law regime in the final diffusive limit. The magnitude of this further time-scale is independent of the index α and may compromise the reliability of applications of Lévy flights to real world cases related with recurrence and transience as optimal searching, animal foraging, and site fidelity.
Practice pharmacists in the primary healthcare team in Aotearoa New Zealand: a national survey
Authors: McDonald Janet , Morris Caroline , Officer Tara N. , Cumming Jacqueline , Kennedy Jonathan , Russell Lynne , McKinlay Eileen , Jeffreys Mona
Published: July 2024

Introduction The integration of pharmacists into general practice settings is increasingly common internationally. Within Aotearoa New Zealand, the role has evolved variably in different regions. Recent health policy and professional guidance support further development. Aim To describe the current status of pharmacists working in primary healthcare settings other than community pharmacy. Methods An online survey of all pharmacists in Aotearoa New Zealand primary healthcare settings was conducted in 2022, and covered employment, current services, patient consultations, relationships with other health professionals, and service costs and benefits. Descriptive statistical analyses were performed. Results Responses from 39 pharmacists (~35% response rate) working in primary healthcare practice roles are reported. Most were female (84%), New Zealand European (81%), and 45% had <5 years’ experience in this setting. The most common service provided was responding to medicines information queries from other health professionals (87%). Most also offered one or more medicines management services: medicines use review (44%), medicines therapy assessment (62%), and medicines optimisation (69%). One-third were prescribing or repeat prescribing pharmacists; non-prescribers expressed strong interest in future prescribing roles. Most (86%) undertook patient consultations with varied capacity to do more. Key perceived benefits for patients included improved health outcomes and medicines understanding; benefits for the health services included supporting the workloads of busy primary healthcare staff. Discussion Practice pharmacists have both patient- and practice-facing roles. The proportion with a prescribing qualification has increased over time. There is some capacity for additional consultations, but this requires funding, space and time spent in a service/setting.
FAM110A promotes mitotic spindle formation by linking microtubules with actin cytoskeleton
Authors: Aquino-Perez Cecilia , Safaralizade Mahira , Podhajecky Roman , Wang Hong , Lansky Zdenek , Grosse Robert , Macurek Libor
Published: July 2024

Precise segregation of chromosomes during mitosis requires assembly of a bipolar mitotic spindle followed by correct attachment of microtubules to the kinetochores. This highly spatiotemporally organized process is controlled by various mitotic kinases and molecular motors. We have recently shown that Casein Kinase 1 (CK1) promotes timely progression through mitosis by phosphorylating FAM110A leading to its enrichment at spindle poles. However, the mechanism by which FAM110A exerts its function in mitosis is unknown. Using structure prediction and a set of deletion mutants, we mapped here the interaction of the N- and C-terminal domains of FAM110A with actin and tubulin, respectively. Next, we found that the FAM110A-Δ40-61 mutant deficient in actin binding failed to rescue defects in chromosomal alignment caused by depletion of endogenous FAM110A. Depletion of FAM110A impaired assembly of F-actin in the proximity of spindle poles and was rescued by expression of the wild-type FAM110A, but not the FAM110A-Δ40-61 mutant. Purified FAM110A promoted binding of F-actin to microtubules as well as bundling of actin filaments in vitro. Finally, we found that the inhibition of CK1 impaired spindle actin formation and delayed progression through mitosis. We propose that CK1 and FAM110A promote timely progression through mitosis by mediating the interaction between spindle microtubules and filamentous actin to ensure proper mitotic spindle formation.
The discursive manifestation of normativities in coming-out-to-family
discourses in Japanese social media
Authors: Saito Junko
Published: July 2024

This study investigates the discursive manifestation of
normativities and participants’ orientation to them for identity work in
coming-out-to-family discourses in Japanese YouTube videoclips posted by
self-identified gay men. The study focuses on how the participants – the
YouTubers and their family members – use discourses of normativity as a resource
to illegitimize and legitimize sexual identities. It also touches on the
conceptualization of homonormativity in the Japanese context. The analysis
suggests that in societies like that of Japan, where heteronormative ideals are
deeply entrenched in the culture, homonormativity may not be fully
conceptualized at the level of local gay male communities, while the dominant
heterosexual community, conversely, may have a clear vision of homonormativity
for these individuals. It thus further considers the viewpoints that shape
normativities for marginalized social groups.
The impact of owner personality traits and cat lifestyle decisions on cat-related guilt
Authors: Kogan Lori R. , Currin-McCulloch Jennifer , Packman Wendy , Bussolari Cori
Published: July 2024

Introduction: The current study aimed to expand current knowledge on cat-related guilt beyond work cat conflict and guilt about cat parenting to determine the influence of owner’s personality traits, choices regarding their cat’s lifestyle, and cat-related guilt factors. Additionally, we sought to assess potential predictors of anxiety and depression to determine the contributions of cat-related guilt, owner personality traits, and social compensatory behaviors, while controlling for owner demographics. Methods: An online, anonymous, cross-sectional survey was disseminated between October 18 and 28, 2023. Survey respondents (n = 531) were adults who resided in the United States and were the primary caretakers of a cat they had owned for at least 6 months. Descriptive statistics captured cat owner demographics. Multiple linear regression was used to predict guilt about cat parenting, work cat conflict, anxiety, and depression. Results: Significant predictors of guilt about cat parenting included guilt factors, time away, indoor, and attention. Significant predictors of work cat conflict included gender and cat guilt factors, time away, and attention. Work cat conflict and personality traits (extraversion, agreeableness, conscientiousness, and neuroticism) significantly predicted depression scores. Lastly, anxiety scores were significantly predicted by work cat conflict, neuroticism, and social compensatory behaviors. Discussion: Findings from this study extend understanding of cat owner’s guilt and illuminate how their personality traits, compensatory behaviors, and lifestyle choices for their pets influence how they perceive and internalize feelings about their cat parenting practices. The nuanced nature of parenting guilt receives limited social recognition, leaving owners isolated in their disenfranchised guilt which significantly influences feelings of anxiety and depression. Our findings underscore the imperative for research and public education about beneficial ways to integrate social contact and enrichment activities to foster both human and animal wellbeing.
Reconstructing the shape and material parameters of dissipative obstacles using an impedance model
Authors: Askham Travis , Borges Carlos
Published: July 2024

In inverse scattering problems, a model that allows for the simultaneous recovery of both the domain shape and an impedance boundary condition covers a wide range of problems with impenetrable domains, including recovering the shape of sound-hard and sound-soft obstacles and obstacles with thin coatings. This work develops an optimization framework for recovering the shape and material parameters of a penetrable, dissipative obstacle in the multifrequency setting, using a constrained class of curvature-dependent impedance function models proposed by Antoine et al (2001 Asymptotic Anal.
26 257–83). We find that in certain regimes this constrained model improves the robustness of the recovery problem, compared to more general models, and provides meaningfully better obstacle recovery than simpler models. We explore the effectiveness of the model for varying levels of dissipation, for noise-corrupted data, and for limited aperture data in the numerical examples.
Cellular response to plasma-generated electrical and chemical stimulation of equal electricity
Authors: Nakayama Airi , Liu Siwei , Yano Ken-ichi , Nakajima Tomoki , Sato Takehiko
Published: July 2024

Plasma medicine is a novel field of research that has the potential in life sciences, including cancer treatment. It has been believed that all of these potential applications depend on the chemical factor of the plasma. However, the electrical factors that are produced simultaneously with the chemical factors have not been researched thoroughly. To assess the effect of plasma on the response of cells, a system that enables simultaneous comparison of the effects of chemical and electrical factors of plasma with equal electricity was invented. This system separates the polarity of plasma and isolates the chemical species from the electric stimulation. Using this system, HT-1080 cells were exposed to plasma for 10 min, 1 h, and 24 h. The 10 min plasma treatment showed a clear difference in the polarity of plasma, where cells under exposure to positive plasma died while cells in other conditions survived. An hour of plasma treatment affected the cells under the negative plasma, where the cell viability was reduced to half. Meanwhile, the electric stimulation did not affect the cell viability but did alter the cell membrane. Collectively, this study demonstrates the differential effects of three factors (electric factor, positive plasma, negative plasma) under the same condition: both the electrical and chemical effects of plasma-generated stimuli with equal amounts of electricity were successfully observed.
Cylindrical Kadomtsev–Petviashvili equation for ion acoustic waves with double spectral indices distributed electrons
Authors: Tufail Nimra , washa Gul , Ullah Shakir , Wahab Muhammad Ali Hussein Abdul , Affan Hira , Rekik Najeh , Farooq Umer
Published: July 2024

We study theoretically and numerically the nonlinear propagation of ion acoustic waves (IAWs) in plasma. The electrostatic potential in electron-ion (e-i) plasma is mimicked by the cylindrical Kadomtsev–Petviashvili equation using the traditional reductive perturbation approach. By applying the direct integration technique, the soliton solution is obtained. The results of simulations carried out numerically show that the amplitude as well as width of the soliton solution are significantly influenced by the plasma parameters. The exploration of IAWs propagation in laboratory as well as space plasmas may benefit from the current work.
Reprogrammable metasurface design for NIR beam steering and active filtering
Authors: Hajian Hodjat , Proffit Matthieu , Ozbay Ekmel , Landais Pascal , Bradley A Louise
Published: July 2024

Reprogrammable metasurfaces enable active modulation of light at subwavelength scales. Operating in the microwave, terahertz, and mid-infrared ranges, these metasurfaces find applications in communications, sensing, and imaging. Electrically tunable metasurfaces operating in the near-infrared (NIR) range are crucial for light detection and ranging (LiDAR) applications. Achieving a NIR reprogrammable metasurface requires individual gating of nano-antennas, emphasizing effective heat management to preserve device performance. To this end, here we propose an electrically tunable Au–vanadium dioxide (VO2) metasurface design on top of a one-dimensional Si–Al2O3 photonic crystal (PC), positioned on a SiC substrate. Each individual Au–VO2 nano-antenna is switched from an Off to ON state via Joule heating, enabling the programming of the metasurface using 1-bit (binary) control. While operating as a nearly perfect reflector at

λ
0

=
1.55

μ

m

, the materials, thickness, and number of the layers in the PC are carefully chosen to ensure it acts as a thermal metamaterial. Moreover, with high optical efficiency (R ∼ 40% at

λ
0

), appropriate thermal performance, and feasibility, the metasurface also enables broadband programmable beam steering in the

1.4
−
1.7

μ

m

range for a wide steering angle range. This metasurface design also offers active control over NIR light transmittance, reflectance and absorptance in the wavelength range of

0.75
−
3

μ

m

. These characteristics render the device practical for LiDAR and active filtering.
Vertically stacked van der Waals heterostructures for three-dimensional circuitry elements
Authors: Miao Jinshui , Fang Yueyue , Jiang Yu , Long Siyu , Dong Yi , Kang Mengyang , Li Tangxin , Wang Jinjin , Fu Xiao , Sun Hui , Wang Hailu
Published: July 2024

Two-dimensional (2D) layered materials have been actively explored for electronic device applications because of their ability to form van der Waals heterostructures with unique electronic properties. Vertical integration of atomically thin 2D materials can enable the design of a three-dimensional (3D) circuit which is a promising pathway to continuously increase device density. In this study, we vertically stack 2D materials, such as graphene (Gr), MoS2, and black phosphorus (BP) to build transistors, heterostructure p–n diodes, and 3D logic circuits. The vertical transistors built from MoS2 or BP semiconductor exhibit a good on-off ratio of up to 103 and a high current density of ∼200 Acm−2 at a very small V
DS of 50 mV. The Gr/BP/MoS2 vertical heterostructure p–n diodes show a high gate-tunable rectification ratio of 102. Finally, we have demonstrated a 3D CMOS inverter by vertical integration of Gr, BP (p-channel), Gr, MoS2 (n-channel), and a 50-nm-thick gold film in sequence. The ability to vertically stack 2D layered materials by van der Waals interactions offers an alternative way to design future 3D integrated circuits.
Evaluation of cartilage properties from NIR diffuse reflectance spectra: numerical simulation
Authors: Rovnyagina Nataliya , Davydov Denis , Lazarev Vladimir , Lychagin Alexey , Timashev Peter , Budylin Gleb , Shirshin Evgeny
Published: July 2024

Diseased conditions of articular cartilage such as osteoarthritis (OA) are accompanied by a change in the water concentration, together with a decrease in cartilage thickness. These parameters are important indicators of the normal joint functioning. Light scattering in a heterogeneous joint tissue is a complex process and it is important to supplement its study with understanding gained from modelling. In this work we employed Monte Carlo for analysis of the relationship between changes in cartilage parameters and calculated diffuse reflectance spectra. It has been shown that water absorption peak at 980 nm is determined by both water content and cartilage thickness, while changes in diffuse reflectance spectra at 1450 nm are mostly driven only by water content. Since independent assessment of these parameters is clinically relevant, several approaches for their determination were developed. A heuristic algorithm for cartilage thickness determination and its quality metrics (R
2 = 0.96) were obtained. Several regression models were developed using the amplitudes of diffuse reflectance spectra at different wavelengths and it was shown that the use of a wide range of wavelengths (850–1700 nm) allows to determine the cartilage water concentration and its thickness with the accuracy R
2 0.96 and 0.99 while measuring at different probe-detector distances.
Effect of monolayer ratio on single-shot all-optical switching in Gd/Fe multilayers
Authors: Jiang Caijian , Liu Donglin , Song Xinyu , Tan Suiyan , Xu Chudong
Published: July 2024

Ultrafast thermally induced magnetization switching (TIMS) with femtosecond lasers has attracted much attention due to its ability to trigger a single switching on the picosecond time scale. Currently, most of the studies on TIMS have focused on various ferrimagnetic alloys. In this paper, TIMS of Gd/Fe multilayers in different monolayer ratios is investigated by atomic spin dynamics. The results show that an increase in the monolayer Gd ratio narrows the energy density window of the switching. Further studies found that a lower damping ratio decreases the laser energy density threshold for magnetization reversal. Moreover, reducing the ratio of Gd in the monolayer at the appropriate energy density can shorten the duration of the transient ferromagnetic-like state, which can lead to faster realization of TIMS. Our simulation results provide new insights to explore the physical mechanism of TIMS in Gd/Fe multilayers.
Design optimization of wide-gate swing E-mode GaN HEMTs with junction barrier Schottky gate
Authors: Tian Kuiyuan , Zhao Yapeng , Du Jiangfeng , Yu Qi
Published: July 2024

To increase the gate swing, a GaN-based high-electron-mobility transistor with a junction barrier Schottky gate (JBS-HEMT) was proposed. Compared to conventional p-GaN Schottky gate HEMTs (Conv-HEMT), the high electric field at the surface is transferred to the pn junction inside the body, and the extended depletion region of the pn junction shields the surface Schottky contact interface for the JBS-HEMT. After fitting the model to the reported device, the proposed JBS-HEMT was simulated and optimized using the Sentaurus TCAD tool. The simulation results of the optimized JBS-HEMT demonstrate a high gate breakdown voltage (17.6 V), which is 158.5% higher than the gate breakdown voltage of the Conv-HEMT (11.1 V) and a lower gate leakage current of six orders of magnitude than the Conv-HEMT at the gate-to-source voltage of 10 V. The proposed JBS-HEMT exhibits a positive threshold voltage (1.68 V) and excellent threshold voltage stability, and the maximum threshold voltage drift of the JBS-HEMT (+0.237 V) is smaller than that of the Conv-HEMT (−0.714 V) under gate stress conditions. The peak transconductance of the JBS-HEMT (186 mS mm−1) at athe drain-to-source voltage of 10 V showed almost no reduction compared to the Conv-HEMT (189 mS mm−1), which solves the problem of decreased transconductance capability of the reported GaN HEMT with a p-n junction gate (PNJ-HEMT). It was confirmed that the JBS-HEMT has excellent gate stability and potential for power electronics applications.
Hybrid simulation of a capacitive Ar/SiH4 discharge driven by electrically asymmetric voltage waveforms
Authors: Zhang Yi-Fan , Dong Wan , Jia Wen-Zhu , Song Yuan-Hong
Published: July 2024

Voltage waveforms associated with the electrical asymmetry effect (EAE) have the potential to be used in the deposition of the silicon-based film, since they are expected to decouple ion energy and flux at the wafer surface, and further facilitate control of the process. In this study, a one-dimensional fluid/electron Monte Carlo hybrid model is employed to examine the EAE in a capacitively coupled argon-silane discharge, encompassing both amplitude asymmetry effect (AAE) and slope asymmetry effect (SAE). In the case of AAE, with the increasing pressure, the discharge electronegativity gradually intensifies, in conjunction with a transition of the electron heating mode from α to drift-ambipolar, a reduction of the absolute value of the DC self-bias voltage, and a decrease in Ar+ content, with an increase in SiH3
+ content. For SAE, the trend in the discharge characteristics with the increasing pressure is similar to that for AAE, but the details are different. In SAE, the electronegativity and bulk electric field are much enhanced, resulting in higher content of high-energy electrons and Ar+ in the bulk. In addition, the absolute value of the self-bias is lower, but shows a fewer decline with the increasing pressure. The deposition rate is lower in SAE, due to the lower electron heating efficiency. However, larger voltage drop difference between two sheaths leads to a wider range of ion energy modulation at higher pressures. This study systematically investigates and compares Ar/SiH4 discharges driven by two electrically asymmetric voltage waveforms across various parameters including electron dynamics, ion and neutral transport properties, and deposition rates, with the aim of providing valuable insights and a reference for industrial applications.
Harmonic voltage measurement based on capacitive equipment dielectric equivalent model and responding current
Authors: Du Lin , Feng Hui , Li Xin , Shao Xianjun , Yang Zhi
Published: July 2024

With the increasing proportion of new energy and the power electronic equipment in the power grid, accurate measurement of harmonic voltage has become increasingly important for power quality monitoring. In order to solve the problem of high-precision measurement of harmonic voltage in the power grid, this manuscript proposes a high-precision harmonic voltage measurement method based on the dielectric equivalent model (DEM) of capacitive equipment and its responding current. Based on DEM, a voltage-current transfer function of the capacitive equipment is established, and harmonic voltage is reconstructed with the responding current. Considering the dielectric relaxation characteristics of capacitive equipment other than a pure capacitor model, this manuscript analyzes the fitting performance of different equivalent capacitance models and improves the traditional pure capacitance model to a more suitable DEM for harmonic voltage reconstruction. The DEM parameters of capacitive equipment are obtained through the frequency domain spectroscopy and intelligent parameter identification algorithms, which improved the measurement accuracy of harmonic voltage and reduced computational complexity. The harmonic voltage testing platform is established to test the simulated high-voltage harmonics and the harmonic voltage of the actual grid voltage. The results show that the proposed harmonic voltage measurement method can meet the high-precision reconstruction of harmonic voltage in the frequency range of 50–2500 Hz, and the system testing error with sensors is less than 2%. The testing accuracy is higher than traditional voltage transformers and testing systems based on pure capacitance models.
A novel simulation-assisted transfer method for bearing unknown fault diagnosis
Authors: Huang Fengfei , Li Xianxin , Zhang Kai , Zheng Qing , Ma Jiahao , Ding Guofu
Published: July 2024

Supervised data-driven bearing fault diagnosis methods rely on completed datasets of faults, which can be challenging for signals collected in real engineering. Recognizing unknown faults using a data-driven approach is particularly difficult, as purposefully modeling these faults is complex. To address this challenge, this study proposes a new simulation-assisted transfer bearing unknown fault diagnosis method for realizing unknown compound fault diagnosis of rotating machinery. Firstly, finite element method is used to obtain the compound fault data that does not exist in the historical data, and wavelet packet transform is performed on the simulated and measured signals to enhance the detailed features of the signals. Then, a deep convolutional feature fusion network based on hybrid multi-wavelet spatial attention is constructed to fuse the time-frequency information processed by different wavelet bases. Finally, by integrating the concepts of intra-class splitting and transfer learning, the model is fine-tuned using simulation data to recognize unknown compound faults of rolling bearings. The method validates the simulated signals’ feasibility and the unknown faults’ diagnostic validity under the publicly available rolling bearings dataset. Compared to the comparison methods, the method’s accuracy increased by 2.86%, 2.61%, 5.41%, 4.77%, and 7.07%, respectively.
Three-dimensional contour detection method based on fusion of machine vision and laser radar
Authors: Jun Wu , Shuo Huang , Shaobo Yuan , Long Jin , Runxia Guo , Jiusheng Chen
Published: July 2024

In the current methods of point cloud processing, there are still several limitations, particularly in achieving high precision and accuracy for large objects in complex environments. Existing techniques often struggle with incomplete or noisy data, leading to inaccurate contour extraction. In view of the challenges associated with the sparse and discrete nature of point clouds in complex environments, which lead to poor accuracy and stability in object contour extraction, this paper proposes a novel method for accurately extracting the contours of three-dimensional target point clouds. The method integrates high-resolution images with sparse point cloud information to address these issues. Firstly, the local characteristics of the point cloud are calculated, allowing for the selection of a contour point cloud. Next, depth information from two-dimensional images is obtained through a fuzzy mapping relationship. Finally, constraint conditions are established to derive a more accurate predicted value of the contour point cloud. Experiments demonstrate that the proposed method effectively improves the precision and accuracy of contour extraction for large objects, reducing measurement deviation by approximately 64.9% compared to using the original point cloud alone. Additionally, the method shows a more accurate completion effect on parts of the contour that are missing, underscoring its robustness and effectiveness in challenging scenarios.
Stationary prospective cardiac gated computed tomography—dynamic study in phantoms and in vivo
Authors: Billingsley Alex , Inscoe Christina , Attia Mohamed Fathy , Lu Jianping , Zhou Otto , Lee Yueh Z
Published: July 2024

Objective. This study explores the feasibility of a stationary gantry cardiac gated computed tomography (CT) with carbon nanotube (CNT) linear x-ray source arrays. Approach. We developed a stationary gantry CT system utilizing multipixel CNT x-ray sources. Given the advantages of straightforward x-ray pulse control with these sources, we investigated the potential for gated prospective imaging. We implemented prospective respiratory and cardiac gating control and evaluated the system through dynamic phantom imaging studies followed by imaging of a porcine model. Main Results. The findings revealed minimal anatomical motion artifacts in the heart and lungs, confirming successful physiologic gated acquisition in stationary gantry cardiac CT. This indicates the potential of this imaging approach for reducing artifacts and improving image quality. Significance. This study demonstrates the feasibility of prospective physiological gating with CNT x-ray sources in a stationary gantry setup for cardiac imaging. This approach could potentially alleviate the need for beta blocker administration during cardiac CT scans, thereby increasing the flexibility of the imaging system and enabling the imaging of a wider variety of patient cardiac conditions.
The advent of quantum computer music: mapping the field
Authors: Miranda Eduardo Reck
Published: July 2024

Quantum computing technology is developing at a fast pace. The impact of quantum computing on the music industry is inevitable. This paper maps the emerging field of quantum computer music. Quantum computer music investigates, and develops applications and methods to process music using quantum computing technology. The paper begins by contextualising the field. Then, it discusses significant examples of various approaches developed to date to leverage quantum computing to learn, process and generate music. The methods discussed range from rendering music using data from physical quantum mechanical systems and quantum mechanical simulations to computational quantum algorithms to generate music, including quantum AI. The ambition to develop techniques to encode audio quantumly for making sound synthesisers and audio signal processing systems is also discussed.
Liquid crystals from curved colloidal rods: waves, twists and more
Authors: Fernández-Rico Carla , Dullens Roel P A
Published: July 2024

The curvature of elongated microscopic building blocks plays a crucial role on their self-assembly into orientationally ordered phases. While rod-like molecules form a handful of liquid crystal (LC) phases, curved or banana-shaped molecules show more than fifty phases, with fascinating physical properties, such as chirality or polarity. Despite the fundamental and technological importance of these so-called ‘banana-shaped liquid crystals’, little is known about their microscopic details at the single-molecule level. Curved colloidal liquid crystals—liquid crystals formed by curved colloidal rods—are excellent model systems to optically resolve the structure and dynamics of curved building blocks within these condensed phases. Recent advances in the synthesis of curved rod-like particles have unlocked the potential for studying—at the single-particle level—the intimate relationship between shape and phase symmetry, and even confirmed the stability of elusive LC phases. Further developments in this nascent field promise exciting findings, such as the first observation of the colloidal twist-bend nematic phase or the fabrication of functional materials with curvature-dependent properties. In this Report on Progress, we will highlight recent advances in the synthesis and assembly of curved colloidal liquid crystals and discuss the upcoming challenges and opportunities of this field.
A new hybrid auxetic structure capable of uniform deformation exhibits excellent energy absorption
Authors: Deng Yunfei , Jin Yaoxiang , Li Hailin , Wang Xuan
Published: July 2024

As a kind of mechanical metamaterial, auxetic honeycomb with negative Poisson’s ratio has received extensive attention in recent years. In order to further improve the stable deformation and energy absorption of the auxetic structure, we combined the asymmetrical re-entrant honeycomb with the triangular honeycombs to propose a new two-dimensional (2D) auxetic structure named asymmetrical re-entrant triangular honeycomb (ART). By setting up comparative experiments, quasi-static compression tests for ART and two existing honeycomb structures (re-entrant star-shaped honeycomb and re-entrant hexagonal honeycomb) along in-plane directions were conducted. A series of ART configurations with different parameters were established, and finite element simulation was used to explore the effects of parameters on the mechanical properties of ART. The unilateral horizontal maximum strain is cited to assess the deformation stability of the structures. The experimental and simulation results show that the deformation of ART is uniform in both in-plane directions. In the compressive strain range that we studied, the specific energy absorption of ART in both directions can be up to 291% and 271% higher than that of the existing structures, respectively, providing excellent load-bearing and energy absorption. In addition, the mechanical properties of ART can be adjusted by changing the geometrical parameters to provide ideas for structural design.
Theoretical analysis and experimental research of piezoelectric-electromagnetic hybrid vibration energy harvester
Authors: Zhang Xuhui , Cheng Yujun , Yang Wenjuan , Pan Jianan , Chen Xiaoyu , Xu Hengtao , Tian Hao , Zhang Jialin
Published: July 2024

To address the concerns of single-mode energy harvesters’ low output power and inefficient energy utilization, this paper proposes a novel piezoelectric–electromagnetic hybrid vibration energy harvester to enhance energy harvesting performance. In order to obtain the dynamic properties and evaluate the efficiency of the proposed hybrid energy harvester, an electromechanical coupling dynamic model was established, and the corresponding voltage, current, and output power of the hybrid energy harvester were calculated. The dynamical responses of the hybrid energy harvester obtained in the numerical simulations were discussed to reveal the influence of key parameters such as the excitation amplitude, load resistance, and initial magnetic distance. Then the validation experiments were conducted to verify the numerical simulation results. The results indicated that the excitation amplitude had a significant effect on the output voltage and output power. Meanwhile, the optimum load resistance and magnetic distance could boost the power generating performance of the hybrid energy harvester. The total output power of the hybrid energy harvesters can reach to 38.2 mW, which is 164.6% and 60.5% higher than those of the corresponding piezoelectric and electromagnetic energy harvesters, respectively. The results of this paper provide a new method for enhancing the performance of vibration energy harvester by means of hybrid energy conversion mechanism from an experimental and theoretical point of view.
Engineering the active layer of lead-free perovskite (CH3NH3SnI3) solar cells using numerical simulation
Authors: Yadav Sarita , Gupta Saral K , Negi C M S
Published: July 2024

We conduct a thorough numerical simulation to examine the impact of the thickness, defect density, and doping density of the active layer on the photovoltaic performance of the lead-free CH3NH3SnI3 perovskite solar cell (PSC). We observe that increasing the thickness of the active layer initially from 100 nm to 400 nm improved the power conversion efficiency (PCE) from 10.4% to 11.6%. However, further increasing the thickness to 800 nm resulted in a slight decline in PCE to 11.1%. This unexpected trend can be attributed to the high carrier mobility of charges in the CH3NH3SnI3 perovskite, which enables fast extraction of charge carriers, offsetting losses due to charge recombination. Increasing active layer trap density substantially declines the PCE from 11.5% at 1014 cm−3 to 7.5% at 1018 cm−3, as a result of the noticeable drop in open-circuit voltage (VOC) and fill factor (FF) with a growing defect density due to the enhancement in trap-assisted recombination. This is backed by a striking reduction in the shunt resistance upon increasing the defect density. Raising the active layer doping firstly enhances the PCE, reaching a peak value of 12.5% at the active layer doping density of 1017 cm−3, after which the PCE decreases as the doping density continues to increase. We explain these observations by energy level diagrams deduced at various doping levels.
Microstructural and electrochemical properties of Co3O4 porous nanospheres
Authors: Afrooze Anjum , Shaik Dadamiah PMD
Published: July 2024

In this study, Co3O4 porous nanospheres were synthesized at 200 °C using a solution combustion method and subsequently annealed at 600 °C. The microstructural and electrochemical properties of these nanostructured Co3O4 samples are thoroughly investigated. X-ray diffraction (XRD) analysis of all samples revealed prominent peaks corresponding to the (220), (311), (222), (400), (422), (511), and (440) planes, which are indicative of the Co3O4 cubic structure with the space group Fd 3̄ m (227). Raman spectroscopy confirmed the presence of Co–O bonds and provided insights into the Functional groups of the samples. Scanning Electron Microscopy (SEM) was employed to examine the materials’ dimensions and surface architecture, revealing detailed features of the porous nanospheres. X-ray Photoelectron Spectroscopy (XPS) analysis verified the presence of Co2+ and Co3+ ions alongside O2− in a spinel configuration, confirming the chemical state of the constituents. Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analyses showed characteristic of porous material. The electrochemical performance of the Co3O4 porous nanospheres was evaluated in a 1M KOH aqueous electrolyte. The as-prepared samples exhibited a maximum capacitance of 309 F g−1 at a current density of 1 A g−1, along with enhanced electrochemical stability, maintaining a significant proportion of their initial capacitance even after 2000 cycles.