bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of carrier recombination coefficients of 3C- and 6H-SiC: Insights into recombination mechanisms in stacking faults of 4H-SiC
Authors: Tanaka Kazuhiro , Kato Masashi
Published: August 2023

In recent years, 4H-SiC power devices have been widely employed in power electronic systems owing to their superior performance to Si power devices. However, stacking faults in 4H-SiC can degrade the device performance. Stacking faults can be considered as polytype inclusions in 4H-SiC. Carrier recombination in stacking faults is considered a cause for performance degradation. Understanding carrier recombination in different polytypes other than 4H-SiC can be helpful in understanding the mechanism of performance degradation due to stacking faults in 4H-SiC. Therefore, in this study, we characterized the recombination coefficients of 3C- and 6H-SiC and compared them with those of 4H-SiC using the time-resolved free-carrier absorption measurement method. Recombination at the stacking faults in 4H-SiC cannot be considered as the intrinsic recombination of inclusions of other polytypes.
Nanoscale Schottky contacts to GaN: Theoretical study and a brief review
Authors: Kim Hogyoung , Choi Byung Joon
Published: August 2023

Nanostructured GaN materials, including nanowires and nanorods, are advantageous for nanoscale devices, owing to their higher surface-to-volume ratio than thin films. Despite the technological progress, there exist many issues to be solved for commercial applications. To realize nanostructured GaN devices, it is essential to figure out thoroughly the current transport mechanisms with regard to the nanoscale contact size. Experimental and theoretical studies have shown that the transport properties in nanoscale Schottky contacts are quite different from those in thin-film based contacts. In this article, theoretical models reported by other researchers are considered to calculate the potential profiles near the metal/GaN interfaces and the current transport mechanisms in nanoscale contacts are investigated. In addition, the results on the nanoscale Schottky contacts to GaN are reviewed to throw light on important issues in GaN nanoscale devices.
Impact ionization in silicon at low charge-carrier energies
Authors: Korpusenko Mikhail , Vaskuri Anna , Manoocheri Farshid , Ikonen Erkki
Published: August 2023

Photons absorbed in silicon produce electron–hole pairs, which can cause impact ionization and quantum yield larger than one. Reliable determination of quantum yield at low charge-carrier energies (<4 eV) has been challenging because photon losses due to reflectance and charge-carrier losses due to recombination affect the resulting photocurrent. Here, we present how the measurement of this fundamental characteristic of silicon crystals can be improved in the charge-carrier energy range of 1.6–4 eV by using a predictable quantum efficient detector based on induced junction photodiodes optimized for photon-to-electron conversion efficiency. The measured quantum yield values are compared with the results of theoretical calculations, revealing increased impact-ionization probabilities at 2.25 and 3.23 eV on the top of a smooth background curve calculated by a model based on free charge carriers in the silicon lattice. For the results at the lowest energies, both data and an asymptotic extrapolation model suggest that quantum yield exceeds unity by ∼10−4 at 1.6 eV corresponding to a photon wavelength of 450 nm.
The challenge of providing medical follow-up for sexual assault victims: can we predict who will attend? A retrospective cross-sectional study
Authors: Healey L. M. , Hutchinson J. L. , Pfeiffer M. N. , Garton L. , Hatten B. , Dobbie M. , Simpson L. , Templeton D. J.
Published: August 2023

This study examined the impact of a pathway between a sexual assault service and a public sexual health service developed to improve rates of post-sexual assault medical follow-up. Follow-up attendances improved in the first 12 months of the pathway (2014) compared with attendances in 2013 (17.8% vs 9.6%, P = 0.01). Factors independently associated with attendance at follow-up were being prescribed HIV post-exposure prophylaxis and knowing the assailant. Those with physical injuries were less likely to attend. The prevalence of sexually transmissible infections in this cohort, 8% at the acute presentation and 5% at follow-up, suggests a need for alternatives to clinic-based follow-up.
IX International Conference on Forest Fire Research and 17th International Wildland Fire Safety Summit: introduction to special issue (Part 3)
Authors: Ribeiro Luís Mário , Viegas Domingos Xavier , Almeida Miguel
Published: August 2023

The ninth International Conference on Forest Fire Research, organised by the Forest Fire Research Center of the Association for Developmental of Industrial Aerodynamics every 4 years since 1990, was held in November 2022 in Coimbra, Portugal. The conference was held in conjunction with the 17th International Wildland Fire Safety Summit, sponsored by the International Association of Wildland Fire. The number and quality of the submissions for this joint event was very high, and the authors were encouraged to submit a full paper to a special issue of the International Journal of Wildland Fire (IJWF). Given the large number of submissions, the Journal decided to publish the special issue in several parts. Part 1 was published in January 2023, with eight papers, and Part 2 in March 2023, with 10 papers. This third part presents 15 original papers in five topical areas: decision support systems and tools (3), risk reduction (2), risk assessment (3), wildland urban interface (3) and wildfire management and safety (4). All the papers in this special issue are published Open Access.
Ants combine object affordance with latent learning to make efficient foraging decisions
Authors: Poissonnier Laure-Anne , Hartmann Yannick , Czaczkes Tomer J.
Published: August 2023

The affordance of an object refers to its functional properties. For example, a bowl has the affordance of holding water, but a sieve does not. Here, we report that ants learn the affordance of a novel object without this attribute being rewarded, and use the memory of this affordance to avoid predicted, but never experienced, crowding. Ants were trained to feeders, which could support either only one ant or many. Two feeders were encountered, each of identical design but differently scented. After training, on the outward journey, half the ants encounter nestmates, which had fed on food matching one of the training feeders. Encountering returning nestmates reduced preference for the feeder matching the scent of the encountered nestmates, but only for ants trained on a limited-access feeder; ants trained on an unlimited feeder were unaffected. In other words, only if ants know that the food access is limited, and receive information that this feeder is heavily visited, do they reduce their preference for this feeder. To achieve this, the ants had to combine memories of the feeders’ affordance with the presence of nestmates. Then they had to use semantic knowledge that restricted food access combined with nestmate presence predicts a likelihood of crowding, or a rule such as “if the food is restricted and there are nestmates on the path, go to another food source.” Regardless of the mechanism, these results demonstrate that ants latently learn the affordance of their surroundings, an unexpected cognitive ability for an invertebrate.
Co-speech gestures can interfere with learning foreign language words*
Authors: Nicoladis Elena , Marentette Paula , Lam Candace
Published: August 2023

Co-speech gestures can help the learning, processing, and memory of words and concepts, particularly motoric and spatial
concepts such as verbs. The purpose of the present studies was to test whether co-speech gestures support the learning of words through gist
traces of movement. We asked English monolinguals to learn 40 Cantonese words (20 verbs and 20 nouns). In two studies, we found support for
the gist traces of congruent gestures being movement: participants who saw congruent gestures while hearing Cantonese words thought they had
seen more verbs than participants in any other condition. However, gist traces were unrelated to the accurate recall of either nouns or
verbs. In both studies, learning Cantonese words accompanied by congruent gestures tended to interfere with the learning of nouns (but not
verbs). In Study 2, we ruled out the possibility that this interference was due either to gestures conveying representational information in
another medium or to distraction from moving hands. We argue that gestures can interfere with learning foreign language words when they
represent the referents (e.g., show shape or size) because learners must interpret the hands as something other than hands.
The nuclear pore complex as a platform for epigenetic regulation
Authors: Brickner Jason H.
Published: August 2023

The nuclear pore complex (NPC) both mediates exchange of proteins and RNA between the nucleus and the cytoplasm and physically interacts with chromatin to regulate transcription. In this issue of JCB, Kumar et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202207060) provide new insight into the molecular basis for NPC-mediated epigenetic silencing through loading of the replication processivity factor PCNA.
Fermions in loop quantum gravity and resolution of doubling problem
Authors: Zhang Cong , Liu Hongguang , Han Muxin
Published: August 2023

The fermion propagator is derived in detail from the model of fermion coupled to loop quantum gravity (LQG). As an ingredient of the propagator, the vacuum state is defined as the ground state of some effective fermion Hamiltonian under the background geometry given by a coherent state resembling the classical Minkowski spacetime. Moreover, as a critical feature of LQG, the superposition over graphs is employed to define the vacuum state. It turns out that the graph superposition leads to the propagator being the average of the propagators of the lattice field theory over various graphs so that all fermion doubler modes are suppressed in the propagator. This resolves the doubling problem in LQG. Our result suggests that the superposition nature of quantum geometry should, on the one hand, resolve the tension between fermion and the fundamental discreteness and, on the other hand, relate to the continuum limit of quantum gravity.
Tuning of electrical, magnetic, and topological properties of magnetic Weyl semimetal Mn 3+x
Ge by Fe doping
Authors: Ghosh Susanta , Low Achintya , Ghorai Soumya , Mandal Kalyan , Thirupathaiah Setti
Published: August 2023

We report on the tuning of electrical, magnetic, and topological properties of the magnetic Weyl semimetal (Mn

3
+
x

Ge) by Fe doping at the Mn site, Mn

(
3
+
x
)
−
δ

Fe

δ

Ge (δ = 0, 0.30, and 0.62). Fe doping significantly changes the electrical and magnetic properties of Mn

3
+
x

Ge. The resistivity of the parent compound displays metallic behavior, the system with δ = 0.30 of Fe doping exhibits semiconducting or bad-metallic behavior, and the system with δ = 0.62 of Fe doping demonstrates a metal–insulator transition at around 100 K. Further, we observe that the Fe doping increases in-plane ferromagnetism, magnetocrystalline anisotropy, and induces a spin-glass state at low temperatures. Surprisingly, topological Hall state has been noticed at a Fe doping of δ = 0.30 that is not found in the parent compound or with δ = 0.62 of Fe doping. In addition, spontaneous anomalous Hall effect observed in the parent system is significantly reduced with increasing Fe doping concentration.
Machine-learned constitutive relations for mechanoluminescent ZnS:Cu–PDMS composites
Authors: Hoover George , Huang Andy , Ryu Donghyeon
Published: August 2023

Materials with novel properties, such as emerging smart materials, offer a design challenge to researchers who want to make use of their unique behaviors. The complex nature of these material responses can be difficult to model from a physics-based understanding as a full description of the multi-physics, multi-scale, and non-linear phenomena requires expertise from various scientific disciplines. Some new smart materials, such as the mechanoluminescent (ML) copper-doped zinc sulfide (ZnS:Cu)-embedded in polydimethylsiloxane (PDMS) (ZnS:Cu–PDMS), lack a constitutive model or an agreement on the mechanisms of action behind the unique material properties. As constitutive equations are essential to engineer devices, with existing knowledge gap in underlying physics of smart materials, a viable approach is to use empirical data for deriving constitutive equations. However, it is challenging to derive constitutive equations on non-linear, multi-variate, and multi-physics relationship using conventional data processing approaches due to the size and complexity of the empirical data. In this work, a machine learning framework is proposed for ones to derive constitutive equations using empirical data for novel materials. The framework is validated by creating constitutive models for ZnS:Cu–PDMS elastomeric composites undergoing a variety of tensile load patterns. To avoid confinement of the models to the programming environment, in which they are developed, numerical fits of the machine-learned models are created as constitutive equations for the non-linear, multi-variate, and multi-physics ML properties. These models can be used when designing ML ZnS:Cu–PDMS to develop devices to harness the unique ML properties.
Exploring the influence of powder particles in dielectric liquid of EDM: pulse train, discharge energy, material removal rate and surface topography
Authors: Rajesh Jonnalagadda Venkata , Giridharan Abimannan
Published: August 2023

A comparative study on the effect of adding molybdenum di-sulphide (MoS2) powders of diameters 40 μm, 90 nm size into an ultrasonic vibration induced dielectric liquid of electrical discharge machining (EDM) process is attempted. Discharge duration, peak current, gap voltage are selected as input variables and their impact is assessed using pulse train, discharge energy, material removal rate (MRR) and surface integrity which are considered as outcome measure. The outcome measures of powder mixed dielectric (PMD) are compared with that of pure dielectric. Through pulse trains, a new phenomenon of partial discharge is identified. The incidence of partial discharge are assessed using scanning electron microscope (SEM) images. By varying the discharge duration, peak current and gap voltage, the discharge energy reduces in contrast to pure dielectric by 4%, 21.01%, 8.35% respectively for 40 μm diameter PMD and 10%, 27.29%, 17.99% respectively for 90 nm diameter PMD. The increase of peak current and gap voltage magnitudes cause the discharge energy to rise whereas discharge energy drops with growing magnitudes of discharge duration. Compared to the pure dielectric, the PMD produced enhanced MRR for similar discharge energy levels. The peak current has shown greater influence on MRR than discharge duration and gap voltage. In comparison with pure dielectric, the machining performance has improved by 21% for 40 μm diameter PMD, whereas 84.21% for 90 nm diameter PMD. At higher discharge parameters, better surface topography is produced in PMD than pure dielectric.
Analyzing the cosmic web environment in the vicinity of grand-design and flocculent spirals with local geometric index
Authors: Sarkar Suman , Narayanan Ganesh , Banerjee Arunima
Published: August 2023

We explore the environment of a combined set of 367 grand-design and 619 flocculent spiral galaxies. We introduce a novel estimator called the local geometric index to quantify the morphology of the local environment of these 986 spirals. The local geometric index allows us to classify the environment of galaxies into voids, sheets, filaments, and clusters. We find that grand-designs are mostly located in dense environments like clusters and filaments (∼ 78%), whereas the fraction of the flocculents lying in sparse environments like voids and sheets is significantly higher (> 10%) than that of the grand-designs. A p-value < 10-3 from a Kolmogorov-Smirnov test indicates that our results are statistically significant at 99.9% confidence level. Further, we note that dense environments with large tidal flows are dominated by the grand-designs. On the other hand, low-density environments such as sheets and voids favor the growth of flocculents.
How to detect lensing rotation
Authors: Robertson Mathew , Lewis Antony
Published: August 2023

Gravitational lensing rotation of images is predicted to be negligible at linear order in density perturbations, but can be produced by the post-Born lens-lens coupling at second order. This rotation is somewhat enhanced for Cosmic Microwave Background (CMB) lensing due to the large source path length, but remains small and very challenging to detect directly by CMB lensing reconstruction alone.
We show the rotation may be detectable at high significance as a cross-correlation signal between the curl reconstructed with Simons Observatory (SO) or CMB-S4 data, and a template constructed from quadratic combinations of large-scale structure (LSS) tracers.
Equivalently, the lensing rotation-tracer-tracer bispectrum can also be detected, where LSS tracers considered include the CMB lensing convergence, galaxy density, and the Cosmic Infrared Background (CIB), or optimal combinations thereof.
We forecast that an optimal combination of these tracers can probe post-Born rotation at the level of 5.7σ–6.1σ with SO and 13.6σ–14.7σ for CMB-S4, depending on whether standard quadratic estimators or maximum a posteriori iterative methods are deployed. We also show possible improvement up to 21.3σ using a CMB-S4 deep patch observation with polarization-only iterative lensing reconstruction.
However, these cross-correlation signals have non-zero bias because the rotation template is quadratic in the tracers, and exists even if the lensing is rotation free. We estimate this bias analytically, and test it using simple null-hypothesis simulations to confirm that the bias remains subdominant to the rotation signal of interest. Detection and then measurement of the lensing rotation cross-spectrum is therefore a realistic target for future observations.
Constraining Horndeski theory with gravitational waves from coalescing binaries
Authors: Quartin Miguel , Tsujikawa Shinji , Amendola Luca , Sturani Riccardo
Published: August 2023

In the broad subclass of Horndeski theories with a luminal speed of gravitational waves,
we derive gravitational waveforms emitted from a compact binary by considering the wave
propagation on a spatially flat cosmological background. A scalar field nonminimally coupled to
gravity gives rise to hairy neutron star (NS) solutions with a nonvanishing scalar charge, whereas
black holes (BHs) do not have scalar hairs in such theories. A binary system containing at least
one hairy neutron star modifies the gravitational waveforms in comparison to those of the BH-BH
binary. Using the tensor gravitational waveforms, we forecast the constraints on a parameter
characterizing the difference of scalar charges of NS-BH or NS-NS binaries for Advanced LIGO and
Einstein Telescope. We illustrate how these constraints depend on redshift and signal-to-noise
ratio, and on different possible priors. We show that in any case it is possible to constrain the
scalar charge precisely, so that some scalarized NS solutions known in the literature can
be excluded.
Constraints on compensated isocurvature perturbations from BOSS DR12 galaxy data
Authors: Barreira Alexandre
Published: August 2023

We use the BOSS DR12 galaxy power spectrum to constrain compensated isocurvature perturbations (CIP), which are opposite-sign primordial baryon and dark matter perturbations that leave the total matter density unchanged. Long-wavelength CIP σ(x) enter the galaxy density contrast as δg
(x) ⊃ bσσ(x), with bσ
the linear CIP galaxy bias parameter. We parameterize the CIP spectra as Pσσ
= A
2
Pℛℛ
and Pσℛ
= ξ√PσσPℛℛ
, where A is the CIP amplitude and ξ is the correlation with the curvature perturbations ℛ. We find a significance of detection of Ab
σ ≠ 0 of 1.8σ for correlated CIP (ξ = 1), consistent with no detection. For uncorrelated CIP (ξ = 0), the constraints are instead more significantly shifted away from zero, although this may be due to large-scale data systematics which have a bigger impact on these type of CIP. The constraints on A depend on the assumed priors for the bσ
parameter, which we estimate using separate universe simulations. Assuming bσ
values representative of all halos we find σA
= 145 for correlated CIP and σ
|A| = 475 for uncorrelated CIP. Our strongest uncorrelated CIP constraint is for bσ
representative of the 33% most concentrated halos, σ
|A| = 197, which is better than the current CMB bounds |A| ≲ 360. We also discuss the impact of the local primordial non-Gaussianity parameter f
NL in CIP constraints. Our results demonstrate the power of galaxy data to place tight constraints on CIP, and motivate works to understand better the impact of data systematics, as well as to determine theory priors for bσ
.
Laser ablation microsampling of copper phthalocyanine blue by the second-harmonic radiation of Nd:YAG laser
Authors: Balakhnina I A , Zagladin A A , Yu Chikishev A , Brandt N N
Published: August 2023

An original nonlinear optical method employing laser ablation with single nanosecond laser pulses at a wavelength of λ = 532 nm is used to study organic paint layer (copper phthalocyanine blue (PB15)). Two processes (photochemical reaction and formation of craters), which appear to be nonlinear result from the pulsed radiation. It is shown that the nonlinear optical procedure (laser ablation microsampling (LAMS)) can be used to obtain microparticles of PB15 sufficient for the further analysis. The Raman spectra of the surface of the paint layer prior to and after LAMS and microparticles are obtained. Spectral data, including those in the low-frequency region, are discussed.
Cryogenic slab RF discharge CO laser with hybrid waveguide-unstable resonators
Authors: Ionin A A , Kozlov A Y , Rulev O A , Sinitsyn D V
Published: August 2023

Dependences of a cryogenic slab radio-frequency discharge CO laser output power on a distance between mirrors of a hybrid negative-branch waveguide-unstable resonator were experimentally studied. The maximum output power was observed at the resonator length longer than the one calculated by taking into account the mirrors radii of curvature. Optimization of the resonator length made it possible to get the output power increase up to 20%–25%. The results obtained can be used for designing not only slab laser systems with hybrid waveguide-unstable resonators, but also for high-power lasers with full-sized negative-branch unstable ones.
Intensity correlation properties of x-ray beams split with Laue diffraction
Authors: Zhao 赵 Chang-Zhe 昌哲 , Si 司 Shang-Yu 尚禹 , Zhang 张 Hai-Peng 海鹏 , Xue 薛 Lian 莲 , Li 李 Zhong-Liang 中亮 , Xiao 肖 Ti-Qiao 体乔
Published: August 2023

Beam splitting is one of the main approaches to achieving x-ray ghost imaging, and the intensity correlation between diffraction beam and transmission beam will directly affect the imaging quality. In this paper, we investigate the intensity correlation between the split x-ray beams by Laue diffraction of stress-free crystal. The analysis based on the dynamical theory of x-ray diffraction indicates that the spatial resolution of diffraction image and transmission image are reduced due to the position shift of the exit beam. In the experimental setup, a stress-free crystal with a thickness of hundred-micrometers-level is used for beam splitting. The crystal is in a non-dispersive configuration equipped with a double-crystal monochromator to ensure that the dimension of the diffraction beam and transmission beam are consistent. A correlation coefficient of 0.92 is achieved experimentally and the high signal-to-noise ratio of the x-ray ghost imaging is anticipated. Results of this paper demonstrate that the developed beam splitter of Laue crystal has the potential in the efficient data acquisition of x-ray ghost imaging.
Phonon dichroism in proximitized graphene
Authors: Shan 单 Wen-Yu 文语
Published: August 2023

We systematically investigate the phonon dichroism in proximitized graphene with broken time-reversal symmetry. We find that in the absence of any type of spin–orbit coupling, phonon dichroism vanishes. Linear and circular phonon dichroism occur in the presence of uniform (staggered) intrinsic spin–orbit coupling and ferromagnetic (antiferromagnetic) exchange coupling. All these situations can be distinguished by their specific behaviors of phonon absorption at the transition point. Our finding provides new possibilities to use phonon dichroism to identify the form of spin–orbit coupling and exchange coupling in proximitized graphene on various magnetic substrates.
Preparation of large-scale uniformly crystallized ITO thin films by rapid infrared annealing technique
Authors: Li Jiaming , Jiang Liangbao , Luo Junjie , Li Xiaoyu , Liu Jiaxi , Wang Minbo , Yan Yue
Published: August 2023

This paper proposes three engineering application technology applications for rapid infrared annealing (RIA): scanning annealing, lamp array preheating and scanning annealing, and lamp array annealing. For the dynamic scanning annealing method, the influence of the working distance from the infrared lamp to the amorphous indium tin oxide (ITO) film and the scanning speed on the heating of the film surface were studied. For lamp array preheating and scanning annealing, the attenuation of the compressive stress on the surface of the chemically strengthened glass under the condition of low temperature and the long holding time were revealed. For lamp array annealing, the influence of this technology on the optical and electrical properties of the ITO film and the surface compressive stress of chemically strengthened glass were studied. Using the lamp array preheating and scanning annealing and lamp array annealing technology, not only a crystalline ITO film with excellent optical and electrical properties and uniformity can be prepared quickly, but also the impact of the crystallization process on chemically strengthened glass can be reduced greatly.
Black Phosphorus Nanosheets: Synthesis and Biomedical Applications
Authors: Zhao Hanjun
Published: August 2023

Since 2014, black phosphorus (BP) has gained more and more attention because of its unique physicochemical properties. In particular, with unique electrical, optical, and biodegradable performances, BP may serve as an alternative for other two-dimensional nanomaterials (2DNMs) in biomedical applications. However, the practical application of BP in the biomedical field still faces great challenges. In this article, we focus on the various synthesis methods of BP, including the exfoliation method, chemical vapor deposition (CVD) method, and wet-chemical self-assembly method, and recent advances of BP in biomedical fields, such as biosensing, imaging, drug delivery, phototherapy, and bioactive phospho-therapy are highlighted. Finally, the current challenges of BP in biomedical applications are briefly discussed. It is believed that this article will provide effective scientific support for the development and application of BP.
Fatigue Performance Analysis of Adhesive-bonded Composite Joints Considering Size Effect
Authors: Liang Jinlong , Tu Liang , Shao Zhenjiang , Tang Ruizhi
Published: August 2023

Adhesive bonding failure is one of the main failure modes threatening the safety of the wind turbine blade (WTB), which drives fatigue performance analysis of adhesive bonding becoming a vital issue. Attributed to the high cost and sample scarcity of full-scale structural testing of WTBs, fatigue analysis of adhesive-bonded composite joints becomes a critical way to investigate the bonding properties. Adhesive bonding distributes in WTB with different sizes; thus, the fatigue performance in different place have a large difference. The existing researches mainly perform fatigue properties studies on the standard specimens, while the effects of bonding size on structural fatigue properties are ignored. With these concerns, a finite element method based on Cyclic Cohesive Zone Model theory is proposed, and size effects on fatigue properties are studied for adhesive-bonded composite joints in this paper. The results can be used for fatigue performance analysis for WTB adhesive bonding.
Microstructure evolution and homogenization parameters optimization of Al-3Cu-1Li-xMg alloys
Authors: Xun Chenyang , Li Xiwu , Li Huiyu , Geng Libo , Chen Pengcheng
Published: August 2023

An ideal homogenization parameter is essential to achieve outstanding final performances from Al-Cu-Li alloys. In this current study, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and differential scanning calorimetry (DSC) techniques were used to examine the evolution of the microstructure of Al-3Cu-1Li-xMg alloys at the homogenization process, where x=0.86 wt.% (Alloy 1#) and x=0.42 wt.% (Alloy 2#). The outcome demonstrates that Ag-containing AlCuMg phases dominated Alloy 1# in its as-cast state. In contrast, Alloy 2# contained more block-like Al2Cu phases. Moreover, the area of the major endotherm peak of the DSC graph increased by 40% in Alloy 1# compared to Alloy 2# due to the addition of Mg concentration. This increases the difficulty of dissolving the soluble in subsequent stages. 495°C/16h+515°C/8h was the optimal homogenization treatment for Alloy 1#, while 495°C/16h was optimal for Alloy 2#. This finding is a benchmark for research on the impact of Mg concentrations on the formation and dissolution of eutectic phases in Al-3Cu-1Li alloys.
The Effect of PH Value on Shear Thickening and Chemical Compound Effect Polishing Solution
Authors: Tang Cheng , Huang Zhifu , Tang Lianyao , Yang Hui , Wang Yage
Published: August 2023

When the traditional polishing method is used to process brittle materials such as lithium niobate, brittle failure is easy to occur, and many microcracks remain on the surface of the workpiece. Thus, the traditional method is not suitable for ultra-precision machining with higher surface roughness requirements. In this paper, a new type of high-performance polishing fluid with shear thickening and chemical compound effect was developed. The shear thickening effect was combined with the chemical effect, which was dedicated to the ultra-precision polishing of difficult-to-machine materials, such as optical crystals and semiconductors. The results show that the best polishing effect is achieved when the pH value is 9.5.
Mechanical Properties of Iron Plating Layer after Nitriding
Authors: Fu Yuzhu
Published: August 2023

A certain thickness of the iron plating layer without impurities was fabricated on the surface of pure iron by employing electroplating treatment. The thickness of the iron plating layer was measured by approximately 23 μm. SEM studies demonstrated the microstructure of the surface of the iron plating layer before and after nitriding. According to XRD analysis, the compound layer was mostly composed of Fe2-3N with high supersaturation of nitrogen. After nitriding, the microhardness of the sample was 555 HV with the depth of the matrix at 30 μm, which was four times the hardness of the matrix. Under the same experimental conditions, the wear volume loss and friction coefficient of the nitrided iron plating layer was lower, showing that nitriding can significantly improve the poor wear resistance of the iron plating layer. The Salt spray corrosion experiment showed that nitriding can significantly improve the corrosion resistance of the iron plating layer.
Study on Effects of Geometric Parameters on Tensile Strength of Hybrid Bonded-Rived Joint of Fiber Reinforced Polymer Plates
Authors: Wang Di , Qu Liyuan , Wang Tianyuanye , Zhan Fei , Du Guangchao , Zhao Lin , Wang Haibo , Chang Zongyu
Published: August 2023

Hybrid bonded-rived joint combines bonding and riveting and has become one of the most important connection forms in composite materials. This paper investigates and analyzes the influence of geometric parameters of CFRP hybrid bonded-rived joints on load-bearing strength. The finite element method is used to analyze the strength of the hybrid bonded/riveted joint between carbon fiber composite and metal under tensile load. The different ratios of the hybrid joint’s e/D, w/D, and w/e are analyzed. It is shown that e/D and w/D significantly impact damage loads and failure mode of the hybrid bonded/riveted joint. The increase of e/D will change the joint from shear-out to net tension failure, and the effect of w/D is opposite to that of e/D. Under the same bonding area, different w/e impacts the damage load of the joint, and the larger w/e makes the joint have a larger failure load, and the stiffness of the joint is also large.
Forming pressure of PMI foam sandwich structure
Authors: Lin Zhengjie , Liang Hengliang , Zhou Hongfei
Published: August 2023

In this study, the performance of A-reinforced sandwich structures made with polymethacrylimide (PMI) foam material is explored. The research focuses on comparing two forming methods, bonding and co-curing. It also tests the static properties of sandwich test pieces under different forming pressures. It reveals that the foam sandwich structure formed under the 0.15 MPa bonding process outperforms the rest regarding static properties. These findings provide valuable insights into the optimal structure-forming process for PMI foam sandwiches, paving the way for future advancements in this field.
Structural Stability of Tailwater Penstock in Xiamen Pumped Storage Power Station
Authors: Li Gaohui , Yang Shaojia
Published: August 2023

To study the external water pressure that can be borne by the steel lining of the tailwater penstock of a pumped storage power station, the optimization of the steel lining shape provides the basis for ensuring its normal operation. In this paper, based on the finite element method and finite element analysis software ABAQUS, the calculation and analysis model of different stiffening ring schemes for tailrace penstock is established, structural stability is calculated and the influence of different stiffening schemes is compared and analyzed. The results show that the structural stability can meet the requirements of the code by setting the T-shaped stiffening ring and longitudinal stiffening rib. With the addition of longitudinal stiffeners, the steel lining tends to the stress characteristics of the two-way slab, and the overall stress deformation tends to be balanced, which can improve the external pressure resistance of the steel lining in the gradual change section to a certain extent.
Study of Large-area Flexible Transistor Array Fabrication
Authors: Chen Zengbian
Published: August 2023

In recent years, the rapid preparation of transistor devices and the control of manufacturing costs have been the focus of researchers. Conventional transistor semiconductor films are usually applied by spin coating or magnetron sputtering. However, the spin coating method tends to cause material waste. Based on this, a method of screen printing semiconductor layers is proposed. In this paper, P3HT ink was obtained by dissolving a mixture of P3HT and ethyl cellulose in a toluene solution. The screen printing technique was used to successfully obtain the semiconductor layer, which in turn successfully printed the transistor array. The dielectric layer is the screen-printed ionic gel and the electrode is vaporized gold electrode, resulting in a 100% success rate of transistors. The operating performance of the device is more stable than that of the spin-coating method, and the switching ratio of the obtained device is stable above 104 when the gate voltage is -3–3 V, -4–4 V, and -5–5 V, respectively. This approach offers a new way of thinking about flexible printed electronics.
Design and analysis of the thermal-insulation panel for the test section of the environmental wind tunnel
Authors: Yu Zebin , Cai Qingqing , Liu Qingnian , Wan Wen
Published: August 2023

Thermal-insulation panels are an important part of the test section for the environmental wind tunnel, which has the function of ensuring uniform airflow temperature and reducing heat loss. Considering many factors such as temperature, humidity, and pressure, it is determined that the average heat dissipation rate of the insulation panel’s outer surface temperature is less than 20 W/m2. The temperature difference between the outer surface of the insulation layer and the environment is not more than 10°C when the airflow temperature inside the test section reaches 95 °C. There is no condensation on the insulation layer when the airflow temperature inside the test section is -10 °C. By comparing various schemes, a phenolic foam was selected as the thermal-insulation material, and process measures such as liquid raw material mixing foaming and special equipment were adopted to complete the fabrication of the panels, and a composite assembly method was adopted to build panels in the test section. The results show that the thermal-insulation panel’s structure is conformed to the requirements of wind-tunnel operation and heat loss, which provides an important basis for reference for the construction of relevant test equipment.
Wear and Life of K40 Carbide Tool for Plunge Milling GH4169
Authors: Chen Hao , Chen Zhuo , Li Lei
Published: August 2023

In order to solve the problems of serious tool wear and poor durability during plunge milling of nickel base superalloy GH4169, the design test obtains the wear morphology process of the tool through K40 carbide tool insertion and milling GH4169. The experiment analyzed the impact and sensitivity of cutting parameters on tool life. The experiment and analysis show that when the K40 carbide tool is the plunge milling GH4169, the service life of the tool decreases rapidly with the increase of cutting speed, feed rate per tooth, and radial cutting depth; The tool life is most sensitive to changes in cutting speed, followed by the feed rate per tooth, and least sensitive to radial cutting depth.
Simulation Study on Lightweight Design of Aluminum Alloy Tube Buffer for Automobile
Authors: Wang Shang , Wang Xuelei , Zhang Yajuan
Published: August 2023

Lightweight is one of the development trends in the automobile industry. Aluminum alloy tube buffers can absorb a lot of energy continuously to protect the personal safety of drivers and other personnel in case of automobile safety accidents. On the premise of not weakening the buffer effect, it is a difficult problem to effectively lightweight the buffer design. To complete the design index of automobile lightweight, the aluminum alloy buffer is studied. In this study, a steel tubular indenter is proposed to replace the original aluminum solid core indenter. Firstly, the finite element model of the original solid-core buffer is established and simulated on the server. Secondly, the simulation results are analyzed, and the effect of the real core indenter on the buffer capacity is very small. Thirdly, the lightweight design scheme is proposed and the new model is established. Finally, the lightweight design scheme is objectively evaluated by taking the energy absorption capacity and the variance of the impact load. The results show that it is feasible to replace the original solid core indenter with a steel tubular indenter. The mass of the new model indenter is reduced from 361.2 g to 252.4 g. The energy absorption value of the new model is the same as that of the original model (1.05 kJ), but the variance of impact load is reduced from 20.22 to 12.60. The lightweight buffer design scheme meets the requirements.
Simulation and Analysis of Three-point Bending Experiment with Hollow Beam Based on Abaqus
Authors: Liang Meiqin , Wang Shang , Peng Fei
Published: August 2023

Bending resistance is a crucial performance indicator for many hollow beams in service. However, traditional three-point bending experiments face challenges in measuring the stress of the inner wall, making it difficult to study the stress distribution and bending resistance of hollow beams under different external loads. In this study, we established a finite element model based on Abaqus and computed on a server to investigate the stress distribution and bending resistance of hollow beams. Our simulation results show that the structure of the beam meets design requirements, and the hollow beam has a bending resistance of 4.26 kN and a maximum stress of 378.6 MPa when the indenter displacement is 1 mm. As the indenter displacement increases to 10 mm, the bending resistance of the hollow beam increases to 9.04 kN, and the maximum stress reaches 636.4 MPa. We also observed stress concentration on the upper and lower sides of the cross-section, with lower stress in the middle region. Statistical analysis of the stress data revealed that the stress value of the nodes decreased as the distance from the center of the sample increased. Our results demonstrate that modeling and simulation are a feasible approach for studying the bending deformation of hollow beams, and this method provides abundant measurement data without size limitations, making it advantageous over traditional experimental measurement. We recommend that more scholars should explore this approach in their research.
Numerical Simulation of Thermal and Stress field of Extreme High-Speed Laser Material Deposition (EHLA) at Different Preheating Temperatures
Authors: Nian Liangxiao , Wang Miaohui , Ge Xueyuan , Wang Xin
Published: August 2023

Extreme high-speed laser material deposition (EHLA) technology is a novel approach to surface modification and component repair that offers benefits, including high cladding efficiency, a low dilution rate, and environmental friendliness. In this research, numerical modeling was used to analyze how varying substrate preheating temperatures affected the temperature field and residual stress of coatings made of 1Cr17Ni2 stainless steel. It was discovered that the peak melt pool temperature was less affected by the substrate preheating temperature. However, the cooling rate and temperature gradient were greatly reduced. When the preheating temperature was 450 °C, the cladding layer showed the lowest temperature gradient and residual stress. The investigation’s findings can be used as a reference to improve the EHLA of 1Cr17Ni2 stainless steel coatings and lessen the possibility of coating cracking.
An experimental investigation on the inkjet printed circuits based on response surface methodology
Authors: Wang Junjie , Hui Jizhuang , Zhang Hao , Yan Zhiqiang , Xu Zhiguang
Published: August 2023

To enhance the electrical conductivity and optimize the morphology of inkjet printed circuits, the response surface method was used to study the effects of Baseboard temperature, Scanning speed, number of layers, and their interactions on Wire width and resistance of printed circuits. Then the regressive equations of the line quality and the analysis of the variance of processing factors on the targeted response were determined. Finally, the optimized results are verified through an additional experiment. Results show the influence of the processing factors on the Wire width and resistance in the following order: Baseboard temperature > several layers > Scanning speed and several layers > Scanning speed > Baseboard temperature, respectively. The optimized parameter configurations are as follows: Baseboard temperature: 57.7 °C, Scanning speed: 1092.3 mm/min, and the number of layers is 2.76. The relative error between the precited data and the measured values is within 5%, which can provide a powerful and valuable reference for selecting processing factors in real manufacturing.
Forensic Analysis of PDC Bits at the Sinopec Shengli Oilfield
Authors: Li Yue , Han Bin , Li Meiyan , Liu Wei
Published: August 2023

Polycrystalline diamond compact (PDC) bit has occupied more than 90% of the total drilling footage in the world. Forensic analysis of dull PDC bits is an important research field that can investigate multiple factors and then find the main failure cause. The findings of the forensic analysis not only guide the selection and placement of the next bit but also promote the advancement of PDC bits. In this study, the PDC bit pulled out of the hole was photographed, and then a forensic analysis was carried out. Based on the analysis of 45 dull PDC bits, the failure causes of PDC bits were divided into three categories: impact, wear, and erosion, which were further divided into ten sub-categories. The correlation between the failure forms and the position of the cutters on the bit tip profile was also investigated. The result shows that the front impact is the dominant failure cause of PDC bits at the Sinopec Shengli Oilfield, which often occurs at the nose and shoulder of the tip profile, while the failure caused by the tip impact is concentrated at the cutters near the OD (outside diameter) position. The results would assist the selection and deployment of the PDC bit.
Topological design and high-performance additive manufacturing of porous femoral implants
Authors: Hao Yi , Liu Zhiqiang , Yao Chun , Liang Yuyao , Li Yinqi
Published: August 2023

The use of porous implants can successfully address the issues of stress shielding and sterile loosening associated with the use of solid implants in the human body. Implant structures can be designed and produced using topology optimization (TOP) and selective laser melting (SLM). In this paper, a unit-optimized structure with better mechanical properties is obtained by topology optimization as the femoral implant constitutive unit. The orthogonal experiment is used to optimize the process parameters of SLM molding Ti-6Al-4 V material to determine the optimal process parameters based on the judging criterion of density. Finally, the SLM technique is used to mold the optimized porous femoral implants. The results of the above study are found as follows: The volume fraction of the optimized cell structure is effectively reduced to 30%, effectively solving the stress shielding problem. Based on the optimal process parameters, the surface of the SLM molded porous femoral implant is clear, with good connection to adjacent unit structures and no overhang on the surface, indicating good molding quality. The application of high-performance porous femoral implants is made possible by this work.
A New Method for Improving Static and High Frequency Magnetic Properties of Fe67Co18Si11B4 Amorphous Alloy
Authors: Wang DongMeng , Ding Yanhong , Ma Xu , Li Yan
Published: August 2023

Rapidly quenched ribbons with a composition of Fe67Co18Si11B4 have been investigated. Surface leveling on the ribbon-free surface leads to the decline of the interior stress of Fe67Co18Si11B4 amorphous alloy, making a decrease of coercivity and a great improvement of static magnetic properties. Free surface leveling treatment can improve the AC magnetic properties of the Fe67Co18Si11B4 amorphous alloy. In high frequency region 106 Hz < f < 108 Hz, the quality factor Q > 3 can be achieved after surface leveling. Free surface leveling is an attractive method to achieve improvements in both static and high frequency magnetic properties.
Study on the Influencing Factors and Forming Process Selection of Sheet Metal Bending Spring Back Defects
Authors: Yang Shanshan , Peng Engao , Zheng Baoqi , Huang Zihan
Published: August 2023

In recent years, with navigation, aviation, chemical manufacturing, and automobile bodies increasing requirements for lightweight, high efficiency, and energy saving, quality requirements in the selection of materials and manufacturing process are also improved. However, there is an unavoidable elastic deformation in the process of plastic bending deformation of the panel veneer, and the accuracy of the workpiece is impacted by the spring back phenomenon, which causes dimensional and shape inaccuracies in the panel veneer. The purpose of this paper is to summarize and analyze the phenomenon of flexural spring back caused by material selection and processing techniques and to discuss the solution of the flexion bounce problem from the material selection, processing method, and machining mold, which can be applied to avoid material wastage.