bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated frequency control study of variable speed variable pitch of DFIG load shedding unit based on VSG
Authors: Liu Lei , Zhao Bo , Hu Juan
Published: January 2024

The involvement of wind turbines operating at load shedding levels in primary frequency regulation serves as a crucial technical solution to provide high levels of inertial response capability and frequency regulation capability in power systems with significant proportions of renewable energy. Load-shedding units' frequency regulation capacity is constrained by the optimal operating speed, which prevents the utilization of the rotor's full kinetic energy and consequently limits the system's ability to provide strong inertia support. Additionally, the units are restricted by the maximum speed in the medium wind speed range, resulting in a reduced reserve capacity. The control mechanism of virtual synchronous generator (VSG) can ensure voltage stability at the machine end, and enable real-time tracking of the grid frequency, thereby imparting to wind turbines the on-grid operation characteristics of synchronous generator sets. To achieve this goal, this paper proposes a coordinated frequency control method for variable-speed variable-pitch doubly fed induction generator units based on VSG. Differentiated control strategies are employed for varying wind speed ranges, while an additional frequency control module is utilized to realize frequency regulation functionality. In conjunction with VSG, this approach enhances the inertial response of the units and strengthens their ability to support grid frequency. Simulation results indicate that the proposed control method mitigates the rate of decline in grid frequency and reduces frequency deviation, ultimately promoting grid stability. Additionally, a simulation system was designed based on the conventional four-machine two-area model to verify the effectiveness of this approach.
Comprehensive analysis of read-after-write latency in HfZrOX-based ferroelectric field-effect-transistors with SiO2 interfacial layer
Authors: Kim Haesung , Yang Hyojin , Lee Seongwon , Yun Sanghyuk , Park Junseong , Park Sejun , Lee Ha-Neul , Kim Hyeonsik , Choi Sung-Jin , Kim Dae Hwan , Kim Dong Myong , Kwon Daewoong , Bae Jong-Ho
Published: January 2024

In this paper, a quantitative analysis is performed focusing on the read-after-write latency (RWL) phenomenon in HfOX-based ferroelectric field-effect transistors with a metal-ferroelectric-insulator-semiconductor structure. RWL is scrutinized by modifying two variables: the pulse width (tp) for the “write 1” operation and the operating temperature (T); the response of the charge component is found to follow an emission mechanism. Additionally, we identified a notable change in charge behavior at a specific temperature (Tb), where capture and emission are in balance. Experimental investigations have demonstrated that the activation energy (EA) for these charge components is situated between 0.2 and 0.5 eV, and the Tb is ∼50 °C. By elucidating the relationship between T, tp, remnant polarization (Pr), and Tb, we offer insights into the importance of optimizing tp and Pr on the transient response of the balanced charge and the related RWL phenomenon.
Drag reduction by natural yam mucilage in turbulent flows
Authors: Xie Luo , Shi Peng-fei , Li He-ren , Liu Hao , Hu Hai-bao
Published: January 2024

Nontoxic bio-polymeric drag reducers are of great practical importance. In this work, a new natural and environmentally friendly drag reducer is introduced, which is extracted from the yam. Yam mucilage solutions are highly shear thinning and are insensitive to temperature variation. Their drag-reducing capability is tested in a water tunnel with the injection of yam mucilage solutions at the bottom wall. The main flow speed varies 0.5–2 m/s, and the corresponding bulk Reynolds number (Re) varied from 11 467 to 45 868. The mean concentration profile from the planar laser-induced fluorescence (PLIF) images and the mean velocity profile from the particle image velocimetry (PIV) images are obtained to explain the drag reduction of the yam mucilage solution. A maximum drag-reduction rate (DR) of 25.27% is achieved. The effects of the solution concentration, the injection rate, and the main flow speed on the drag-reduction efficiency are explored. The DR-log10K fitting curve is linear, consistent with that of the reported polymer drag reducers. The K-scaling laws also imply that the consumption of yam mucilage would be much more than that of polyethylene oxide (PEO) corresponding to similar DR. The further revelation of the effective drag-reducing component within the yam mucilage is believed to promote the efficiency of drag reduction. The yam mucilage is a candidate drag-reducing agent that can be an alternative to existing polymer solutions.
Jetting and droplet formation of particle-loaded fluids
Authors: Shi Jing , Cagney Neil , Tatum John , Condie Angus , Castrejón-Pita J. Rafael
Published: January 2024

Inkjet printing is an attractive method for patterning and fabricating objects across many areas of industry. There is a growing interest in the printing of inks with high particle-loading, such as inks containing glass frit, ceramic and functional inks. However, the use of these inks is often limited due to uncertainty regarding the impact of their rheology on the printing process. Understanding of the role of complex rheology in the jetting of loaded inks is therefore needed to facilitate the wider application of inkjet printing. Here, we characterize the complex rheology and the jetting of model dispersion inks (containing 10, 15, and 23 vol. % TiO2 nanoparticles) and compared them with those without particles. The jetting of the model fluids was conducted with a commercial inkjet printhead (nozzle diameter 34 μm) and visualized with stroboscopic and ultra-high-speed imaging. For low particle concentrations, droplet formation is generally similar to those of unloaded inks, provided their Ohnesorge number and Weber number are matched, although the filament of the loaded model fluid tends to have earlier break-off, having a shorter length. The jetting reliability decreased with increase in particle-loading until reliable jetting can no longer be achieved, due to local particle–particle interactions in the ink channel and in the filament during the fast extensional thinning process. A jetting map is presented which illustrates the influence of particle-loading on the droplet formation, and indicates that the acceptable range of Ohnesorge number for jetting is reduced as the particle-loading is increased.
Turbulence characteristics in partially vegetated open channels with alternating sparse and dense patches
Authors: Liu Honghua , Liu Mengyang , Ai Yidan , Huai Wenxin
Published: January 2024

A large amount of vegetation in nature exists in the form of heterogeneous vegetation patches, and variations in vegetation characteristics significantly affect water flow structures. The objective of this study is to investigate the effect of alternating sparse and dense patches on turbulence characteristics. Multiple sets of heterogeneous vegetation scenarios were designed for numerical simulation analysis, and a comparison was made with homogeneous vegetation. Results indicate that compared with that of homogeneous vegetation, the arrangement of heterogeneous vegetation alters the distribution of flow velocities in the vegetation zone and the main channel, promoting material exchange between these regions. The vegetation density difference between sparse and dense vegetation patches in heterogeneous vegetation effect on the main channel increases with larger vegetation density differences, but the magnitude of the effect is limited and generally remains within 10% of the vegetation width. In the balance equation of turbulent kinetic energy, the terms are influenced differently by changes in vegetation density. As vegetation density difference increases, the convective term gradually increases, while the production and diffusion terms exhibit a “lower in the middle, higher at both ends” pattern. The dissipation term demonstrates a reduction effect at low-density differences, gradually increases with larger differences, and ultimately exhibits an amplification effect. Furthermore, this study determines that using data from mid-height to represent the entire cross section for heterogeneous vegetation may result in a maximum error of up to 11%.
Compact high-order gas-kinetic scheme for direct numerical simulation of compressible turbulent flows
Authors: Wang Yibo , Wang Yuhang , Pan Liang
Published: January 2024

In this paper, the three-dimensional fully compact high-order gas-kinetic scheme (HGKS) is proposed for the direct numerical simulation of compressible turbulent flows. Because of the high-order gas evolution model, the numerical fluxes as well as the point-wise conservative variables can be evaluated from the time-accurate gas distribution function at the cell interface. As a result, both the cell-averaged variables and their cell-averaged gradients can be updated inside each cell. Based on the cell averaged values and their gradients, the compact Hermite weighted essentially non-oscillatory (HWENO) scheme is developed, in which the dimension-by-dimension reconstruction is used for three-dimensional turbulences. In both normal and tangential directions, the fifth-order HWENO reconstruction is adopted. Compared with the classical WENO scheme, the stencil for the HWENO scheme only contains 33 cells for each cell. To achieve the temporal accuracy, the two-stage fourth-order temporal discretization is used. For the evaluation of point-wise variables, the simplified third-order gas-kinetic solver is used. Several classical benchmark problems are simulated, which validate the accuracy, resolution, and robustness of compact HGKS. As a comparison, the numerical results of HGKS using non-compact WENO reconstruction are also provided. Due to the compact stencil, the compact HGKS has a favorable performance for turbulence simulation in resolving the multi-scale structures.
A microfluidic cover converts a standard 96-well plate into a mass-transport-controlled immunoassay system
Authors: Wang Sheng , Zhou You , Li Zhenyu
Published: January 2024

96-well microtiter plates, widely used in immunoassays, face challenges such as prolonged assay time and limited sensitivity due to the lack of analyte transport control. Orbital shakers, commonly employed to facilitate mass transport, offer limited improvements and can introduce assay inconsistencies. While microfluidic devices offer performance enhancements, their complexity and incompatibility with existing platforms limit their wide adoption. This study introduces a novel microfluidic 96-well cover designed to convert a standard 96-well plate to a mass-transport-controlled surface bioreactor. The cover employs microfluidic methods to enhance the diffusion flux of analytes toward the receptors immobilized on the well bottom. Both simulation and experimental results demonstrated that the cover significantly enhances the capture rate of analyte molecules, resulting in increased signal strength for various detection methods and a lower detection limit. The cover serves as an effective add-on to standard 96-well plates, offering enhanced assay performance without requiring modifications to existing infrastructure or reagents. This innovation holds promise for improving the efficiency and reliability of microtiter plate based immunoassays.
Pressure-cycling induced transition behaviors of MnBi2Te4
Authors: Wu Jie , Feng Yan , Ren Yifeng , Zhang Ziyou , Yang Yanping , Wang Xinyao , Su Fuhai , Dong Hongliang , Lu Yang , Zhang Xiaojun , Deng Yu , Xiang Bin , Chen Zhiqiang
Published: January 2024

MnBi2Te4 can generate a variety of exotic topological quantum states, which are closely related to its special structure. We conduct comprehensive multiple-cycle high-pressure research on MnBi2Te4 by using a diamond anvil cell to study its phase transition behaviors under high pressure. As observed, when the pressure does not exceed 15 GPa, the material undergoes an irreversible metal–semiconductor–metal transition, whereas when the pressure exceeds 17 GPa, the layered structure is damaged and becomes irreversibly amorphous due to the lattice distortion caused by compression, but it is not completely amorphous, which presents some nano-sized grains after decompression. Our investigation vividly reveals the phase transition behaviors of MnBi2Te4 under high pressure cycling and paves the experimental way to find topological phases under high pressure.
Using the petiole of the miriti palm for the core of a small wind turbine blade
Authors: Gomes I. dos S. , Vaz J. R. P. , Wood D. H.
Published: January 2024

In many small wind turbine blades, the interior space between laminate skins is filled by a material core. The mechanical properties of the core are much less important than its density, which must be low to reduce the moment of inertia as high inertia increases both the starting time of the turbine and the gyroscopic loads on the blades. In this paper, we use, for the first time, the petiole of the miriti palm (PMP) as the core of four small blades, in order to analyze its effect on turbine starting performance. PMP is abundant in the Amazon region and harvesting it does not destroy the palm because the petiole regrows; therefore, harvesting is fully sustainable and may well have a major role in increasing the sustainability on wind turbine manufacturing. We consider the benefits of using the easily worked petiole for the core in terms of manufacturing, as demonstrated by the construction of a 0.598 m blade. PMP is less dense on average than alternative materials, such as expanded polystyrene and balsa wood. The starting performance is an important issue for small wind turbines. It is evaluated using a quasi-steady model, in which blade element momentum theory is coupled to Newton's Second Law. The low density of the small blade made using petiole of the miriti reduces the starting time by 10% when compared with expanded polystyrene and 42% when compared to balsa wood.
Two potential paths for OH radical formation on surfaces of pure water microdroplets
Authors: Skurski Piotr , Simons Jack
Published: January 2024

Experimental findings by others suggest that OH radicals are formed in unexpected abundance on or near surfaces of 1–50 µm microdroplets comprised of pure water, but the mechanism by which these radicals are generated is not yet fully resolved. In this work, we examine two possibilities using ab initio electronic structure methods: (1) electron transfer (ET) from a microdroplet surface-bound OH− anion to a nearby H3O+ cation and (2) proton transfer (PT) from such a H3O+ cation to a nearby OH− anion. Our findings suggest that both processes are possible but only if the droplet’s underlying water molecules comprising the microdroplet provide little screening of the Coulomb interaction between the anion and cation once they reach ∼10 Å of one another. In the ET event, an OH radical is formed directly; for PT, the OH formation occurs because the new O–H bond formed by the transferred proton is created at a bond length sufficiently elongated to permit homolytic cleavage. Both the ET and PT pathways predict that H atoms will also be formed. Finally, we discuss the roles played by strong local electric fields in mechanisms that have previously been proposed and that occur in our two mechanisms.
Eliminating the Tg-confinement and fragility-confinement effects in poly(4-methylstyrene) films by incorporation of 3 mol  % 2-ethylheyxl acrylate comonomer
Authors: Serna Sergio , Wang Tong , Torkelson John M.
Published: January 2024

Nanoconfined poly(4-methylstyrene) [P(4-MS)] films exhibit reductions in glass transition temperature (Tg) relative to bulk Tg (Tg,bulk). Ellipsometry reveals that 15-nm-thick P(4-MS) films supported on silicon exhibit Tg − Tg,bulk = − 15 °C. P(4-MS) films also exhibit fragility-confinement effects; fragility decreases ∼60% in going from bulk to a 20-nm-thick film. Previous research found that incorporating 2–6 mol  % 2-ethylhexyl acrylate (EHA) comonomer in styrene-based random copolymers eliminates Tg- and fragility-confinement effects in polystyrene. Here, we demonstrate that incorporating 3 mol  % EHA in a 4-MS-based random copolymer, 97/3 P(4-MS/EHA), eliminates the Tg- and fragility-confinement effects. The invariance of fragility with nanoconfinement of 97/3 P(4-MS/EHA) films, hypothesized to originate from the interdigitation of ethylhexyl groups, indicates that the presence of EHA prevents the free surface from perturbing chain packing and the cooperative mobility associated with Tg. This method of eliminating confinement effects is advantageous as it relies on the simplest of polymerization methods and neat copolymer only slightly altered in composition from homopolymer. We also investigated whether we could eliminate the Tg-confinement effect with low levels of 2-ethylhexyl methacrylate (EHMA) in 4-MS-based or styrene-based copolymers. Although EHMA is structurally nearly identical to EHA, 4-MS-based and styrene-based copolymers incorporating 4 mol  % EHMA exhibit Tg-confinement effects similar to P(4-MS) and polystyrene. These results support the special character of EHA in eliminating confinement effects originating at free surfaces.
Differences in broiler bone, gut, and tissue mineral parameters, as influenced by broilers grouped based on bodyweight
Authors: Elvis-Chikwem Chinwendu L. , White Gavin A. , Burton Emily , O’Shea Cormac J.
Published: January 2024

Context Variation in bodyweight is an undesirable feature in broiler production. Compositional differences between high- and low-bodyweight (BW) chicks in bone parameters and tissue mineral concentrations may provide insight into underlying causes of variation in BW. Aims This study aimed to investigate differences in bone measurements, tissue mineral concentrations, and gut parameters of Ross 308 male broiler chicks with identical diet and environmental conditions, but with distinct BW on Day 21 (D21). Methods A 3-week growth study was conducted involving 40 male, day-old chicks from the Ross 308 line. Chicks were reared in a deep-litter house with a controlled environment and the same commercial diet. On D21, BW data collected from chicks were used as a criterion to rank them into high- and low-BW groups (n = 11/group). Retrospective BW measurements were compared between groups. Birds were selected for assessing bone parameters, liver mineral profile, gut pH, gizzard neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents. Key results Retrospective BW measurements among the high- and low-BW groups showed a consistent difference in BW between the two groups in early life. Tibial concentrations of manganese and strontium were significantly (P < 0.05) higher in the low-weight (LW) group relative to the high-weight (HW) group. Concentrations of manganese, cadmium and caesium in the liver tissue showed significant differences, with the LW group having higher concentration of these trace elements. The LW chicks had lower gizzard digesta pH, higher gizzard NDF and a statistical tendency for higher ADF concentrations compared to the HW group. Conclusions and implications In summary, broilers ranked on the basis of D21 BW showed differences in tibial bone, gut, and tissue mineral parameters. The LW group had lower gizzard pH and higher gizzard fibre content than did the HW group, which may be attributed to factors such as behavioural activities relating to more litter consumption among the LW group than the HW group.
Environmental DNA detection of spot-tailed quoll from soil is unlikely to be useful for routine monitoring
Authors: White Lauren C. , Nelson Jenny L. , Cardoso Maria , Pacioni Carlo
Published: January 2024

Context Accurate monitoring data on species presence and distribution are crucial for effective conservation management. Environmental DNA (eDNA)-based techniques, in which species are detected from trace amounts of DNA found throughout the environment, are promising tools that may complement traditional monitoring methods and improve detection. However, imperfect detection is a feature of all survey methods that should be properly assessed so that the probability of detecting a target species’ DNA at a site where it is present (i.e. the sensitivity of the method) can be determined. The spot-tailed quoll (Dasyurus maculatus), a carnivorous marsupial found in eastern Australia, is a difficult species to detect as it is rare and has large home ranges, often in remote and difficult to access habitat. Aims In this study, we aimed to evaluate the feasibility of using eDNA soil analysis as a viable alternative or complement to traditional monitoring techniques for detecting spot-tailed quoll. Methods We developed a species-specific assay and validated it using synthetic oligos, tissue samples and soil collected from a captive quoll enclosure. We then assessed the assay on natural environment soil samples taken from the Snowy River region from communal quoll defecation sites (latrines) and from broader quoll habitat. We used amplification success data to model the concentration of quoll DNA in soil from different site types and calculate the sensitivity of our assay. Key results Sensitivity was highest at latrine sites, but decreased sharply when sampling just 1 m away. In non-latrine habitat, the positive amplification rate was too low to allow for meaningful statistical analyses, suggesting that a prohibitively large number of samples would need to be analysed for detection probabilities to be adequate for routine monitoring programs. Conclusions Overall, we found that low sensitivity was driven by the low concentration of spot-tailed quoll DNA at many of the surveyed sites. Implications Given that quoll latrines can usually be identified from the accumulation of scats, and scats themselves can be sampled for DNA, we suggest that eDNA analysis of soil is unlikely to offer improvements over current spot-tailed quoll monitoring methods.
COOLAIR
and PRC2 function in parallel to silence
FLC
during vernalization
Authors: Nielsen Mathias , Menon Govind , Zhao Yusheng , Mateo-Bonmati Eduardo , Wolff Philip , Zhou Shaoli , Howard Martin , Dean Caroline
Published: January 2024

Noncoding transcription induces chromatin changes that can mediate environmental responsiveness, but the causes and consequences of these mechanisms are still unclear. Here, we investigate how antisense transcription (termed
COOLAIR
) interfaces with Polycomb Repressive Complex 2 (PRC2) silencing during winter-induced epigenetic regulation of Arabidopsis
FLOWERING LOCUS C
(
FLC
). We use genetic and chromatin analyses on lines ineffective or hyperactive for the antisense pathway in combination with computational modeling to define the mechanisms underlying
FLC
repression. Our results show that
FLC
is silenced through pathways that function with different dynamics: a
COOLAIR
transcription-mediated pathway capable of fast response and in parallel a slow PRC2 switching mechanism that maintains each allele in an epigenetically silenced state. Components of both the
COOLAIR
and PRC2 pathways are regulated by a common transcriptional regulator (NTL8), which accumulates by reduced dilution due to slow growth at low temperature. The parallel activities of the regulatory steps, and their control by temperature-dependent growth dynamics, create a flexible system for registering widely fluctuating natural temperature conditions that change year on year, and yet ensure robust epigenetic silencing of
FLC.
VOT for plosives in the indigenous languages of Balochistan
Authors: Syed Nasir Abbas , Bibi Shah
Published: January 2024

Different models of L3 acquisition have different predictions about the cross-linguistic effects of previous
learning. The ‘Cumulative Enhancement Model’ predicts that both L1 and L2 have cumulative facilitative effects on L3, but L2 the
Status Factor (L2SF) claims that L2 has stronger effects on L3 acquisition. Similarly, while the Typological Primacy Model claims
that among the already acquired languages, a typologically similar language transfers more properties to L3, the Linguistic
Proximity Model predicts a transfer of structurally similar properties from the previously learnt languages. On the other hand,
the Scalpel Model, besides considering linguistic similarity, gives importance to factors such as frequency of use and nature of
the input, language dominance, and learning context. The current paper contributes to this debate by presenting data collected
from two groups of Balochi learners of English in Balochistan (Pakistan) who were taught British English (BrE) aspiration contrast
in plosives at the allophonic level after they had acquired Pakistani English (PakE) as adult L2 learners. Thus, Balochi was L1,
PakE L2, and BrE L3 of the learners. After teaching for more than a year, the learners were tested for accuracy in VOTs for BrE
plosives. The results support the L2SF and Scalpel Model.
Contradicting potential climate misinformation during televised debates
Authors: Beck Nielsen Søren
Published: January 2024

Experimental research recommends that climate change debaters actively contradict misinformation. This study
examines discursively how participants do so during prominent televised Danish debates, that is, how they orient towards elements
in other participants’ preceding talk about climate change causes and implications as factually wrong. Three types are considered:
(i) contradictions produced by the interviewer in the next turn; (ii) contradictions produced by a co-participant after being
allocated the turn by the interviewer; and (iii) contradictions produced by a co-participant in a self-selected turn. Analysis
reveals that the contradictions are attuned to and limited by these sequential circumstances. The study overall finds that
sequential context significantly impacts climate change debaters’ possibilities for contradicting misinformation; in particular,
potential misinformation may be ‘smuggled’ into multi-unit turns, which can prove difficult for co-panelists to confront because
of the format’s turn-taking provision.
Liposome encapsulated hemoglobin modified Au@TiO2 for sonodynamic therapy
Authors: He Yulu , Zhang Cong , Wang Qian , Weng Yulong , Ran Xia , Kuang Yanmin , Zhang Kun , Guo Lijun
Published: January 2024

Sonodynamic therapy (SDT) has attracted considerable attention owing to its large penetration depth. However, the low efficiency of traditional sonosensitizers and the hypoxia environment of deep tumors hinder their therapeutic effect in practical application. Herein, the Au@TiO2-hemoglobin loaded liposome (Au@TiO2-Hb-Lip) complex has been constructed to improve the efficiency of SDT against hypoxic tumors. The results indicate that the generated carriers upon ultrasound activation of TiO2 nanoparticles (NPs) can be effectively trapped by Au NPs, and the production of reactive oxygen species is increased by two times compared to that of bare TiO2 NPs. Particularly, the introduction of liposomes as a carrier and hemoglobin as an oxygen supplier not only prevents the aggregation of Au@TiO2 NPs in the blood environment but also improves the adaptability of Au@TiO2-Hb-Lip to hypoxic tumors. These synergic actions of different moieties in Au@TiO2-Hb-Lip sonosensitizer significantly enhance the SDT efficiency.
Longitudinal vibration estimation of a mine hoist using a hybrid signal fusion method combining UKF, ND and improved DE
Authors: Chen Xiao , Zhang Chun , Chang Ju-Cai , Zhao Guang-Ming , Zang Wan-Shun , Zhu Zhen-Cai , Shen Gang
Published: January 2024

The monitoring of cage longitudinal vibration can directly indicate the operational status of mine hoists. However, it is always challenging to collect the sensor signals of moving cages with high dynamic characteristics in real time from complex working environments using traditional monitoring methods. In this study, a more practical hybrid signal fusion approach is proposed to realize estimation of cage longitudinal vibration from a low sampling rate acceleration acquisition signal and a low cost encoder signal for state estimation. A nonlinear differentiator is applied to extract encoder differential signals and expand observation variables. An unscented Kalman observer based on nonlinear mine hoist model is designed to estimate the unknown state. To overcome the influence of the uncertain parameters, an improved differential evolution (DE) algorithm combining parameter adaptive method, reverse learning competition scheme and multiple parallel populations strategy is proposed to find unknown parameters of the observation model and autotune the parameters of the algorithms by using low sampling rate acceleration. Sensor data of the simulated experiment platform were collected and processed by the xPC system to validate the effectiveness of the proposed strategy. The experimental results showed that the improved DE (IDE) algorithm had a faster mean time for parameter tuning and the smallest fitness value compared to the standard DE, the particle swarm optimization algorithm and the genetic algorithm. Moreover, the longitudinal vibration estimation system, after parameter tuning by the IDE optimization algorithm, could achieve the purpose of signal estimation, with a smaller estimation error and a better estimation effect.
A weighted sparse classification method based on period analysis dictionary
Authors: Wang Huaqing , Zhang Hongjie , Wang Baoguo , Han Changkun , Song Liuyang
Published: January 2024

The periodic transient shocks triggered by damages in rolling bearings are frequently overshadowed by disruptive elements such as noise and harmonics. Therefore, the extraction of fault characteristics from these disturbances to identify the health status of the bearing is crucial for fault diagnosis. This study presents a novel approach, the period analysis dictionary weighted sparse representation classification (PAD-WSRC) method, designed specifically for rolling bearings. The proposed approach incorporates Bi-damped wavelet as the dictionary wavelet atom, while accounting for the pulse characteristics induced by faults and leveraging prior knowledge of periodicity. A weighted sparse representation (SR) method was also designed, which calculates the weighted SR coefficients of samples, amplifying the local features of samples while addressing the impact of time-shift bias. In addition, the bearing fault type is identified using a mutual correlation classification criterion based on sparse approximation. Our PAD-WSRC strategy has demonstrated its effectiveness in classifying the health status of bearings across three datasets, achieving recognition accuracies of 99.75%, 99.69% and 99.17%, respectively. Comparisons with several traditional methods further underscore the effectiveness and superiority of our proposed method in classifying rolling bearing faults.
Pulmonary nodule detection in x-ray images by feature augmentation and context aggregation
Authors: Liu Chenglin , Wu Zhi , Wang Binquan , Zhu Ming
Published: January 2024

Recent developments in x-ray image based pulmonary nodule detection have achieved remarkable results. However, existing methods are focused on transferring off-the-shelf coarse-grained classification models and fine-grained detection models rather than developing a dedicated framework optimized for nodule detection. In this paper, we propose PN-DetX, which as we know is the first dedicated pulmonary nodule detection framework. PN-DetX incorporates feature fusion and self-attention into x-ray based pulmonary nodule detection tasks, achieving improved detection performance. Specifically, PN-DetX adopts CSPDarknet backbone to extract features, and utilizes feature augmentation module to fuse features from different levels followed by context aggregation module to aggregate semantic information. To evaluate the efficacy of our method, we collect a LArge-scale Pulmonary NOdule Detection dataset, LAPNOD, comprising 2954 x-ray images along with expert-annotated ground truths. As we know, this is the first large-scale chest x-ray pulmonary nodule detection dataset. Experiments demonstrates that our method outperforms baseline by 3.8% mAP and 5.1% AP
0.5. The generality of our approach is also evaluated on the publicly available dataset NODE21. We aspire for our method to serve as an inspiration for future research in the field of pulmonary nodule detection. The dataset and codes will be made in public.
Improvement of lithium battery corner detection accuracy based on image restoration method
Authors: Cheng Hao , Bi Qilin , Chen Xiaoxin , Zheng Hongxin , Du Yixian , Jiang Zhansi
Published: January 2024

Target detection technology has been widely used in the automatic production of lithium batteries. However, motion blur will lead to the reduction of the angular position detection accuracy of lithium batteries. To solve this problem, an improved fuzzy recovery model for angular position of lithium battery is proposed in this paper. Firstly, the improved lightweight neural network RepVGG was used as the main module of the backbone network, so that the network could improve the performance of network feature extraction while reducing the number of calculation parameters and improving the reasoning speed of fuzzy restoration. Secondly, we optimize the multi-Dconv head transposed attention (MDTA) module and reference it to the generator, which reduces the complexity of the model and strengthens the network’s attention to details and textures, and improves the visual effect of the restored image. Finally, we design a lightweight globally connectable residual network called SAC Block and use it to to improve the discriminator, which enhances the global receptive field of the model and improves the structural similarity between the restored image and the original image. In order to verify the effectiveness of the method, we verify it on the self-built dataset and GoPro dataset. The experiments show that our proposed lightweight model improves the peak signal-to-noise ratio (PSNR) index by 9.2% and 8.6% respectively compared with the original model. The visual effect of the restored image is better than that of other current similar algorithms, and it is confirmed that our model can better improve the accuracy of lithium battery angular position detection.
Analog electromagnetic induced transparency of T-type Si-based metamaterial and its applications
Authors: He Mengyue , Wang Qiaoqiao , Zhang Hao , Xiong Jing , Liu Xiangpeng , Wang Junqiao
Published: January 2024

A T-type silicon-based metamaterial is proposed, which realizes electromagnetically induced transparency (EIT) by using the asymmetry of its structure. This dielectric metamaterial exhibits an ultranarrow EIT transparent window, with a transmittance of 91% and a Q factor of 180. Measuring its sensing performance, a refractive index sensor with a sensitivity of 466 nm RIU−1 is obtained. In addition, by analyzing the dispersion characteristics of the structure, the maximum group delay value is 2.84 ps, and the corresponding group refractive index is 4250. Therefore, dielectric metamaterials with this structure are expected to be used in refractive index sensing and slow light devices.
Comparative study of current carrying capacity between 1G and 2G HTS tape samples at different temperatures and magnetic fields
Authors: Yang Tianhui , Li Wenxin , Xin Ying
Published: January 2024

Two categories of high-temperature superconducting (HTS) tapes, the silver-sheathed BSCCO tape (1G HTS tape) and REBCO coated conductor (2G HTS tape), have been commercialized worldwide and widely used in applications. In this study, the 1G HTS tape produced by Sumitomo and 2G HTS tape produced by Superpower were selected for a systematic comparative study in critical current (I
c) performances under various temperature and magnetic field conditions. The anisotropy and I
c variation patterns of these two types of samples in the temperature range of 25–77 K, magnetic field from 0 to 7 T and field angle from 0 to 90° were compared and analyzed. The results of this study reveal certain comprehensive characteristic features of these two categories of HTS tapes, supplementing some new systematic information to the literature.
Dynamic all-optical memory switching based on atomic optical bistable behavior in a three level Λ-type atomic system
Authors: He Haiqiang , Fan Bixuan , Xie Min
Published: January 2024

We theoretically investigate the atomic optical bistability (AOB) in a three-level Λ-type atomic system confined in a unidirectional optical ring cavity. The role of the intensity or detuning of the control field on AOB is explored, and results show that absorption, dispersion, and nonlinearity can be modified significantly by the control field due to quantum coherence and interference in multilevel atomic systems. Thus, tuning the intensity or detuning of the control field can manipulate the switch-up and switch-down thresholds, as well as the area of the bistable hysteresis loop. According to the controllability of AOB, we design various schemes to realize dynamical all-optical switching between the high and low outputs of two bistable curves for a fixed cavity input. In addition, dynamical all-optical memory switching can be implemented by adding a pulse sequence for the intensity or detuning of the control field. For appropriate parameters, such as the cooperative coefficient, the extinction ratio of the switching can be improved dramatically.
Dark Matter Search in Dwarf Irregular Galaxies with Ten Years of Data from the IceCube Neutrino Observatory
Authors: Lü Yi-Fei , Zhu Ben-Yang , Li Rong-Lan , Guo Xue-Kang , Liu Tian-Ci , Huang Yong-Bo , Liang Yun-Feng
Published: January 2024

Dwarf irregular galaxies (dIrrs), as rotationally supported systems, have more reliable J-factor measurements than dwarf spheroidal galaxies and have received attention as targets for dark matter detection in recent years. In this paper, we use 10 yr of IceCube muon-track data and an unbinned maximum-likelihood-ratio method to search for neutrino signals beyond the background from the directions of seven dIrrs, aiming to detect neutrinos produced by heavy annihilation dark matter. We do not detect any significant signal. Based on such null results, we calculate the upper limits on the velocity-averaged annihilation cross section for 1 TeV–10 PeV dark matter. Our limits, although weaker than the strictest constraints in the literature in this mass range, are also a good complement to the existing results considering the more reliable J-factor measurements of dIrrs.
A Machine Learning Made Catalog of FR-II Radio Galaxies from the FIRST Survey
Authors: Lao Bao-Qiang , Yang Xiao-Long , Jaiswal Sumit , Mohan Prashanth , Sun Xiao-Hui , Qin Sheng-Li , Zhao Ru-Shuang
Published: January 2024

We present an independent catalog (FRIIRGcat) of 45,241 Fanaroff–Riley Type II (FR-II) radio galaxies compiled from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey and employed the deep learning method. Among them, optical and/or infrared counterparts are identified for 41,425 FR-IIs. This catalog spans luminosities 2.63 × 1022 ≤ L
rad ≤ 6.76 × 1029 W Hz−1 and redshifts up to z = 5.01. The spectroscopic classification indicates that there are 1431 low-excitation radio galaxies and 260 high-excitation radio galaxies. Among the spectroscopically identified sources, black hole masses are estimated for 4837 FR-IIs, which are in 107.5 ≲ M
BH ≲ 109.5
M
⊙. Interestingly, this catalog reveals a couple of giant radio galaxies (GRGs), which are already in the existing GRG catalog, confirming the efficiency of this FR-II catalog. Furthermore, 284 new GRGs are unveiled in this new FR-II sample; they have the largest projected sizes ranging from 701 to 1209 kpc and are located at redshifts 0.31 < z < 2.42. Finally, we explore the distribution of the jet position angle and it shows that the faint Images of the FIRST images are significantly affected by the systematic effect (the observing beams). The method presented in this work is expected to be applicable to the radio sky surveys that are currently being conducted because they have finely refined telescope arrays. On the other hand, we are expecting that further new methods will be dedicated to solving this problem.
Real-time estimation of EEG-based engagement in different tasks
Authors: Natalizio Angela , Sieghartsleitner Sebastian , Schreiner Leonhard , Walchshofer Martin , Esposito Antonio , Scharinger Josef , Pretl Harald , Arpaia Pasquale , Parvis Marco , Solé-Casals Jordi , Sebastián-Romagosa Marc , Ortner Rupert , Guger Christoph
Published: January 2024

Objective. Recent trends in brain–computer interface (BCI) research concern the passive monitoring of brain activity, which aim to monitor a wide variety of cognitive states. Engagement is such a cognitive state, which is of interest in contexts such as learning, entertainment or rehabilitation. This study proposes a novel approach for real-time estimation of engagement during different tasks using electroencephalography (EEG). Approach. Twenty-three healthy subjects participated in the BCI experiment. A modified version of the d2 test was used to elicit engagement. Within-subject classification models which discriminate between engaging and resting states were trained based on EEG recorded during a d2 test based paradigm. The EEG was recorded using eight electrodes and the classification model was based on filter-bank common spatial patterns and a linear discriminant analysis. The classification models were evaluated in cross-task applications, namely when playing Tetris at different speeds (i.e. slow, medium, fast) and when watching two videos (i.e. advertisement and landscape video). Additionally, subjects’ perceived engagement was quantified using a questionnaire. Main results. The models achieved a classification accuracy of 90% on average when tested on an independent d2 test paradigm recording. Subjects’ perceived and estimated engagement were found to be greater during the advertisement compared to the landscape video (p = 0.025 and p

<

0.001, respectively); greater during medium and fast compared to slow Tetris speed (p

<

0.001, respectively); not different between medium and fast Tetris speeds. Additionally, a common linear relationship was observed for perceived and estimated engagement (r

rm
= 0.44, p

<

0.001). Finally, theta and alpha band powers were investigated, which respectively increased and decreased during more engaging states. Significance. This study proposes a task-specific EEG engagement estimation model with cross-task capabilities, offering a framework for real-world applications.
Micro ECDM process comparison using different tool feed methods of constant gravity and spring-force
Authors: Nawaz Shan Ali , Cao Peiyao , Tong Hao , Li Yong
Published: January 2024

Quartz glass has been widely used in multiple frontier fields of science and technology owing to its excellent chemical and mechanical properties, such as optical communication, semiconductor, photovoltaic power, and aerospace. ECDM (electrochemical discharge machining) is a non-traditional material removal process suitable for machining non-conductive materials of high hardness and brittleness. The tool electrode feed method is a key factor affecting the ECDM process. Experimental research was carried out for comparing the conventional gravity feed method and a newly-developed spring-force feed method. Micro tool electrodes of Φ150 µm were fabricated by combining the method of TF-WEDG (tangential feed-wire electrical discharge grinding) and reverse micro EDM (electrical discharge machining). Machined microstructures of blind holes, channels, squares, and patterns were compared by the gravity feed method and the spring-force feed method respectively. The experimental results show that the spring-force feed method can improve the micro ECDM process considering the aspects of dimensional accuracy, overcuts, deteriorated edges, surface topography, and tool wear.
Electrolytic preparation of two-dimensional layered sulphur nanomaterials and their application in lithium-sulphur batteries
Authors: Peng Jiaming , Shen Lihua , Qin Xubo
Published: January 2024

Currently, two-dimensional (2D) layered materials have gained much attention for their outstanding properties. Among these materials, layered sulphur, which is an emerging 2D material, has shown great potential for various applications due to its unique chemical and physical properties. In this study, we present a new electrolytic method for synthesizing layered sulphur using thiourea as the sulphur source and poly-3,4-ethylenedioxy thiophene/polystyrene sulfonate (PEDOT: PSS) as the stabilizer. This method is simple, fast, and has a high yield. Furthermore, a composite material was prepared containing carbon nanotubes (CNTs) and layered sulphur, which was used a cathode material in lithium-sulphur batteries. The prepared cathode exhibited a discharge specific capacity of 450 mAhg−1and a reversible capacity of 46.6% after 40 cycles of reciprocation at 0.1 C cycling current. Electrode design based on layered sulphur composites provides a new idea for the structural design of lithium-sulphur battery cathodes.
Covalent-organic framework film: From synthesis and structure to energy, catalysis and sensor applications
Authors: Chen Xinyi , Xu Xiaofeng , Li Yanhua
Published: January 2024

Films are used a lot in nature, especially with animals and plants. With the development of film technology, it is becoming more popular and being used applied in many fields. There has been a growing trend to make covalent-organic framework (COF) films, which was inspired by the development of COF. Compare with traditional polymer, COF is a new polymer form that not only has high stability, but also functional diversity and designability. With these characteristics, COF film will create new possibilities for many applications. In this review, we summarize the major progress made on the synthetic strategies of COF film and their applications in energy, catalysis, and sensor application. Finally, we discuss the existing issues and future direction.
Anti-thermal Quenching in Blue Phosphor Ba3YAl2O7.5: Tm3+
Authors: Bian Xiaomin , Fu Hao
Published: January 2024

Blue-emitting phosphors are essential components of the color plasma display panel (PDP), white light-emitting diodes (W-LEDs), and liquid crystal display (LCD) backlights. However, the thermal quenching effect of the phosphor is a serious problem in practice. In this work, a new kind of blue phosphor Ba3YAl2O7.5: xTm3+ was prepared and the luminescent characteristic and thermal stability were studied. Under 358 nm excitation, the phosphors produced a blue emission peak centered at 461 nm, which is due to the transition of Tm3+ from level 1D2 to 3F4. Moreover, the optimal sample Ba3YAl2O7.5: 0.03Tm3+ shows an anti-thermal quenching effect in which the emission intensity at 210 °C rises to 120 % of that at 30 °C , attributable to the presence of oxygen vacancy defects. The result indicates that the Ba3YAl2O7.5: Tm3+ with excellent thermal stability is a promising blue phosphor for lighting and display fields.