bluuebunny/crossref_metadata_2025 huggingface dataset:
Remaining useful life prediction of bearings using a trend memory attention-based GRU network
Authors: Li Jingwei , Li Sai , Fan Yajun , Ding Zhixia , Yang Le
Published: January 2024

Remaining useful life (RUL) prediction of bearings holds significant importance in enhancing the reliability and durability of rotating machinery. Bearings undergo a gradual degradation process that unfolds over multiple stages. In this paper, a novel framework for forecasting the RUL of bearings is put forward, which includes the construction of a health indicator with a stage division algorithm (SDA) and the estimation of the health indicator using a new trend memory attention-based gated recurrent unit (TMAGRU). The SDA, based on the K-Means++ algorithm and angle recognition algorithm, is introduced to distinguish the degradation stage based on the health indicator. Inspired by the double exponential smoothing technique and attention mechanism, the proposed TMAGRU network effectively incorporates both the historical health information in the slow degradation stage and its trend. Experimental results conducted on IEEE PHM Challenge 2012 dataset and XJTU-SY dataset demonstrate the superior predictive performance of the proposed approach compared to several state-of-the-art predictive networks.
Silicon nitride thermo-optic on-chip Mach–Zehnder interferometer at visible wavelengths
Authors: Wang Xiaomin , Ji Peirui , Li Shaobo , Wang Fei , Deng Huiwen , Yang Shuming
Published: January 2024

On-chip Mach–Zehnder interferometer (MZI) is a fundamental component for many integrated systems. It holds great promise in photonic applications at visible wavelengths. This paper presents an on-chip silicon nitride thermo-optic MZI. It is capable of generating interference at a wide wavelength range in the visible spectrum, including 488 nm, 532 nm, and 633 nm. The optical transmission loss is reduced by optimizing the device architecture. This work provides new insights into the designing of integrated optics and demonstrates the potential applications of on-chip MZI in the field of visual measurement.
Low-temperature diffusion in thin-film Pt-(Au-)-Co heterostructures: a structural and magnetic characterization
Authors: Pedan Roman , Makushko Pavlo , Yavorskyi Yurii , Dubikovskyi Oleksandr , Bodnaruk Andrii , Burmak Andrii , Golub Vladimir , Voloshko Svitlana , Hübner René , Makarov Denys , Vladymyrskyi Igor
Published: January 2024

Formation of functional thin films for nanoelectronics and magnetic data storage via thermally induced diffusion-driven structural phase transformations in multilayer stacks is a promising technology-relevant approach. Ferromagnetic thin films based on Co Pt alloys are considered as a material science platform for the development of various applications such as spin valves, spin orbit torque devices, and high-density data storage media. Here, we study diffusion processes in Pt–Co-based stacks with the focus on the effect of layers inversion (Pt/Co/substrate versus Co/Pt/substrate) and insertion of an intermediate Au layer on the structural transitions and magnetic properties. We demonstrate that the layer stacking has a pronounced effect on the diffusion rate at temperatures, where the diffusion is dominated by grain boundaries. We quantify effective diffusion coefficients, which characterize the diffusion rate of Co and Pt through the interface and grain boundaries, providing the possibility to control the homogenization rate of the Pt–Co-based heterostructures. The obtained values are in the range of 10−16–10−13 cm2 s−1 for temperatures of 150 °C–350 °C. Heat treatment of the thin-film samples results in the coercivity enhancement, which is attributed to short-range chemical ordering effects. We show that introducing an additional Au intermediate layer leads to an increase of the coercive field of the annealed samples due to a modification of exchange coupling between the magnetic grains at the grain boundaries.
Phosphorus-doped TiO2 mesoporous nanocrystals for anodes in high-current-rate lithium ion batteries
Authors: Ko Wen-Yin , Wu Tung-Ching , He Sin-Yu , Lin Kuan-Jiuh
Published: January 2024

Limited by the intrinsic low electronic conductivity and inferior electrode kinetics, the use of TiO2 as an anode material for lithium ion batteries (LIBs) is hampered. Nanoscale surface-engineering strategies of morphology control and particle size reduction have been devoted to increase the lithium storage performances. It is found that the ultrafine nanocrystal with mesoporous framework plays a crucial role in achieving the excellent electrochemical performances due to the surface area effect. Herein, a promising anode material for LIBs consisting of phosphorus-doped TiO2 mesoporous nanocrystals (P-TMC) with ultrafine size of 2–8 nm and high specific surface area (234.164 m2 g–1) has been synthesized. It is formed through a hydrothermal process and NaBH4 assisted heat treatment for anatase defective TiO2 (TiO2–x) formation followed by a simple gas phosphorylation process in a low-cost reactor for P-doping. Due to the merits of the large specific surface area for providing more reaction sites for Li+ ions to increase the storage capacity and the presence of oxygen vacancies and P-doping for enhancing material’s electronic conductivity and diffusion coefficient of ions, the as-designed P-TMC can display improved electrochemical properties. As a LIB anode, it can deliver a high reversible discharge capacity of 187 mAh g–1 at 0.2 C and a good long cycling performance with ∼82.6% capacity retention (101 mAh g–1) after 2500 cycles at 10 C with an average capacity loss of only 0.007% per cycle. Impressively, even the current rate increases to 100 times of the original rate, a satisfactory capacity of 104 mAh g−1 can be delivered, displaying good rate capacity. These results suggest the P-TMC a viable choice for application as an anode material in LIB applications. Also, the strategy in this work can be easily extended to the design of other high-performance electrode materials with P-doping for energy storage.
Direct chemical-vapor-deposition growth of alloyed perovskite microcrystals for tunable emissions
Authors: Shen Xia , Wu Yu , Dang Chanjuan , Li Pu , Guo Pengfei
Published: January 2024

Tunable composition of perovskite micro/nanostructures are perfect candidate for the designing of multifunctional optoelectronic circuits. Especially, integrated polychromatic luminescence based on the perovskite materials along a single substrate or chip is essential to the integrated photonic devices and multicolor displays. Here, we reported a synthesis of composition tunable CsPbI3(1–x)Br3x
(X = 0.65–0.9) perovskite microstructures on a single substrate via a magnetic-pulling CVD method. The PL emissions can be changed gradually from green (558 nm, 2.23 eV) to red (610 nm, 2.03 eV) under a focused 375 nm laser illumination. Furthermore, these composition-graded alloyed perovskite microcrystals show stable emissions after six months in air, which may find applications in multicolor display and broad band light sources in the future.
Structural phase transition and resistive switching properties of Cu
x
O films during post-thermal annealing
Authors: Seo Juwon , Kim Taeyoung , Kim Yoonsok , Jeong Mun Seok , Kim Eun Kyu
Published: January 2024

We studied the phase change and resistive switching characteristics of copper oxide (Cu
x
O) films through post-thermal annealing. This investigation aimed to assess the material’s potential for a variety of electrical devices, exploring its versatility in electronic applications. The Cu
x
O films deposited by RF magnetron sputtering were annealed at 300, 500, and 700 °C in ambient air for 4 min by rapid thermal annealing (RTA) method, and then it was confirmed that the structural phase change from Cu2O to CuO occurred with increasing annealing temperature. Resistive random-access memory (ReRAM) devices with Au/Cu
x
O/p+-Si structures were fabricated, and the ReRAM properties appeared in CuO-based devices, while Cu2O ReRAM devices did not exhibit resistive switching behavior. The CuO ReRAM device annealed at 500 °C showed the best properties, with a on/off ratio of 8 × 102, good switching endurance of ∼100 cycles, data retention for 104 s, and stable uniformity in the cumulative probability distribution. This characteristic change could be explained by the difference in the grain size and density of defects between the Cu2O and CuO films. These results demonstrate that superior and stable resistive switching properties of RF-sputtered Cu
x
O films can be obtained by low-temperature RTA.
Stacking-induced phonon transport engineering of siligene
Authors: Cao Haibin , Luo Yufeng , Jiao Wenyan , Lei Wen , Han Shihao , Liu Huijun
Published: January 2024

Tunable phonon transport properties of two-dimensional materials are desirable for effective heat management in various application scenarios. Here, we demonstrate by first-principles calculations and Boltzmann transport theory that the lattice thermal conductivity of siligene could be efficiently engineered by forming various stacking configurations. Unlike few-layer graphene, the stacked siligenes are found to be covalently bonded along the out-of-plane direction, which leads to unique dependence of the thermal conductivity on both the stacking order and layer number. Due to the restricted flexural phonon scattering induced by the horizontal reflection symmetry, the AA stacking configuration of bilayer siligene exhibits obviously higher thermal conductivity compared with the AB stacking. In addition, we observe increasing thermal conductivity with the layer number, as evidenced by the reduced phonon scattering phase space and Grüneisen parameter. Interestingly, the Fuchs-Sondheimer model works well for the thickness-dependent thermal conductivity of stacked siligenes.
A model-based direct inversion network (MDIN) for dual spectral computed tomography
Authors: Zhou Haichuan , Zhang Huitao , Zhao Xing , Zhang Peng , Zhu Yining
Published: January 2024

Objective. Dual spectral computed tomography (DSCT) is a very challenging problem in the field of imaging. Due to the nonlinearity of its mathematical model, the images reconstructed by the conventional CT usually suffer from the beam hardening artifacts. Additionally, several existing DSCT methods rely heavily on the information of the spectra, which is often not readily available in applications. To address this problem, in this study, we aim to develop a novel approach to improve the DSCT reconstruction performance. Approach. A model-based direct inversion network (MDIN) is proposed for DSCT, which can directly predict the basis material images from the collected polychromatic projections. The all operations are performed in the network, requiring neither the conventional algorithms nor the information of the spectra. It can be viewed as an approximation to the inverse procedure of DSCT imaging model. The MDIN is composed of projection pre-decomposition module (PD-module), domain transformation layer (DT-layer), and image post-decomposition module (ID-module). The PD-module first performs the pre-decomposition on the polychromatic projections that consists of a series of stacked one-dimensional convolution layers. The DT-layer is designed to obtain the preliminary decomposed results, which has the characteristics of sparsely connected and learnable parameters. And the ID-module uses a deep neural network to further decompose the reconstructed results of the DT-layer so as to achieve higher-quality basis material images. Main results. Numerical experiments demonstrate that the proposed MDIN has significant advantages in substance decomposition, artifact reduction and noise suppression compared to other methods in the DSCT reconstruction. Significance. The proposed method has a flexible applicability, which can be extended to other CT problems, such as multi-spectral CT and low dose CT.
UC-stack: a deep learning computer automatic detection system for diabetic retinopathy classification
Authors: Fu Yong , Wei Yuekun , Chen Siying , Chen Caihong , Zhou Rong , Li Hongjun , Qiu Mochan , Xie Jin , Huang Daizheng
Published: January 2024

Object. The existing diagnostic paradigm for diabetic retinopathy (DR) greatly relies on subjective assessments by medical practitioners utilizing optical imaging, introducing susceptibility to individual interpretation. This work presents a novel system for the early detection and grading of DR, providing an automated alternative to the manual examination. Approach. First, we use advanced image preprocessing techniques, specifically contrast-limited adaptive histogram equalization and Gaussian filtering, with the goal of enhancing image quality and module learning capabilities. Second, a deep learning-based automatic detection system is developed. The system consists of a feature segmentation module, a deep learning feature extraction module, and an ensemble classification module. The feature segmentation module accomplishes vascular segmentation, the deep learning feature extraction module realizes the global feature and local feature extraction of retinopathy images, and the ensemble module performs the diagnosis and classification of DR for the extracted features. Lastly, nine performance evaluation metrics are applied to assess the quality of the model’s performance. Main results. Extensive experiments are conducted on four retinal image databases (APTOS 2019, Messidor, DDR, and EyePACS). The proposed method demonstrates promising performance in the binary and multi-classification tasks for DR, evaluated through nine indicators, including AUC and quadratic weighted Kappa score. The system shows the best performance in the comparison of three segmentation methods, two convolutional neural network architecture models, four Swin Transformer structures, and the latest literature methods. Significance. In contrast to existing methods, our system demonstrates superior performance across multiple indicators, enabling accurate screening of DR and providing valuable support to clinicians in the diagnostic process. Our automated approach minimizes the reliance on subjective assessments, contributing to more consistent and reliable DR evaluations.
Detection of negative ions in streamer discharge in air by transient cavity ringdown spectroscopy
Authors: Fushimi Kimika , Shirai Naoki , Sasaki Koichi
Published: January 2024

Atmospheric-pressure discharges generated in air are expected to be electronegative, but experiments that examine negative ion densities are limited to date. In this work, we measured the temporal variation of the negative ion density in a streamer discharge generated in air. We adopted cavity ringdown spectroscopy, where negative ions were detected via weak optical absorption caused by laser photodetachment. The temporal variation of the absolute negative ion density was deduced by the transient analysis of the ringdown curve. Negative ions were detected after the disappearance of the discharge voltage and current. The negative ion density started the increase at 0.4 µs after the initiation of the discharge. The increase means the enhancement of the electron attachment frequency in the late phase of the secondary streamer with electron cooling. The survival of electrons until 0.4 µs is understood by the steep decrease in the cross section of dissociative recombination with the electron energy. The maximum negative ion density was observed at 1 µs, and it was around the noise level at 1.5 µs. The rapid decay is consistent with the destruction of negative ions by mutual neutralization with positive ions.
Color image encryption algorithm based on quantum random walk and multiple reset scrambling*
Authors: Mou Dingkang , Dong Yumin
Published: January 2024

In order to address the issues of privacy breaches, data tampering, and security threats in the realm of image encryption and information security, it is essential to ensure the confidentiality, integrity, and reliability of image data. In this paper, we propose a novel hybrid color image encryption scheme that increases the complexity of the key space and provides better data integrity protection by combining the quantum random walk and SHA-256 algorithm. At the same time, three chaotic systems were combined, and multiple XOR operations were introduced to effectively scramble the spatial and pixel levels of the color image. Through numerous simulation experiments and security analyses, the results demonstrate that the solution exhibits efficient encryption performance, excellent resistance to attacks, and outstanding privacy protection capabilities.
Synergistic effects of graphene additives and piston ring surface treatment on friction properties of engine oil
Authors: Zhou Long , Wang Hongshuo , Sun Guanghua
Published: January 2024

The use of nano-additives improves the performance of lubricants by minimizing energy loss due to friction and wear. In this study, tribological properties of cylinder liner-piston ring were improved by modifying monolayer graphene with surfactants. Additionally, surface chemical chromium coating and chemical heat treatment were conducted on the friction surfaces of specially made piston ring samples to further enhance the friction of piston ring. From the comparison of experimental results, the best lubrication performance was exhibited by the use of 0.05 wt% modified graphene nano-lubricant, which reduced the friction coefficient by approximately 31.1% and improved the anti-wear performance by approximately 59.6% compared to the base oil. In addition, the effect of the graphene nano-lubricant on the friction performance of chromium-coated samples was more substantial than that of the chemically heat-treated samples. Under high-temperature and heavy-load conditions, the corresponding friction coefficient was reduced by 15.5% and 34%, respectively, when compared to the base oils. This can be attributed to the porous surface of the chromium-coated sample, which promotes the storage of the graphene nano-lubricant. The results highlight the synergistic effect of graphene additives and piston ring surface treatment on the tribological performance.
Port-based entanglement teleportation via noisy resource states
Authors: Kim Ha Eum , Jeong Kabgyun
Published: January 2024

Port-based teleportation (PBT) represents a variation of the standard quantum teleportation and is currently being employed and explored within the field of quantum information processing owing to its various applications. In this study, we focus on PBT protocol when the resource state is disrupted by local Pauli noises. Here, we fully characterise the channel of the noisy PBT protocol using Krauss representation. Especially, by exploiting the application of PBT for entanglement distribution necessary in realizing quantum networks, we investigate entanglement transmission through this protocol for each qubit considering noisy resource states, denoted as port-based entanglement teleportation (PBET). Finally, we derive upper and lower bounds for the teleported entanglement as a function of the initial entanglement and the noises. Our study demonstrates that quantum entanglement can be efficiently distributed by protocols utilizing large-sized resource states in the presence of noise and is expected to serve as a reliable guide for developing optimized PBET protocols. To obtain these results, we address that the order of entanglement of two qubit states is preserved through the local Pauli channel, and identify the boundaries of entanglement loss through this teleportation channel.
Studies of reflection asymmetry in heavy nuclei
Authors: Butler P A
Published: January 2024

For certain combinations of protons and neutrons it is expected that the shape of atomic nuclei can undergo octupole deformation, which would give rise to reflection asymmetry or a ‘pear shape’. Here it is described how recent experiments carried out at CERN using the HIE-ISOLDE facility to accelerate radioactive beams and detect the subsequent γ-emission using the Miniball spectrometer have provided evidence that several radium and radon isotopes have either stable pear shapes or are octupole vibrational in nature. Their behaviour is compared with that of nuclei with A ≈ 150 exhibiting strong octupole correlations. It will be shown that the data on transition moments present some challenges for theory. The relevance of these measurements for atomic EDM searches will also be discussed.
Confronting dark matter freeze-in during reheating with constraints from inflation
Authors: Becker Mathias , Copello Emanuele , Harz Julia , Lang Jonas , Xu Yong
Published: January 2024

We investigate the production of particle Dark Matter (DM) in a minimal freeze-in model considering a non-instantaneous reheating phase after inflation.
We demonstrate that for low reheating temperatures, bosonic or fermionic reheating from monomial potentials can lead to a different evolution in the DM production and hence to distinct predictions for the parent particle lifetime and mass, constrained by long-lived particle (LLP) searches.
We highlight that such scenario predicts
parent particle decay lengths larger compared to using the instantaneous reheating approximation. Moreover, we demonstrate the importance of an accurate definition of the reheating temperature and emphasize its relevance for the correct interpretation of experimental constraints.
We explore different models of inflation, which can lead to the considered reheating potential. We find that the extent to which the standard DM freeze-in production can be modified crucially depends on the underlying inflationary model. Based on the latest CMB constraints, we derive lower limits on the decay length of the parent particle and confront these results with the corresponding reach of LLP searches.
Our findings underscore the impact of the specific dynamics of inflation on DM freeze-in production and highlight their importance for the interpretation of collider signatures.
At the same time, our results indicate the potential for LLP searches to shed light on the underlying dynamics of reheating.
Non-perturbative ⟨ϕ⟩, ⟨ϕ2 ⟩ and the dynamically generated scalar mass with Yukawa interaction in the inflationary de Sitter spacetime
Authors: Bhattacharya Sourav , Choudhury Moutushi Dutta
Published: January 2024

We consider a massless minimally coupled self interacting quantum scalar field coupled to fermion via the Yukawa interaction, in the inflationary de Sitter background. The fermion is also taken to be massless and the scalar potential is taken to be a hybrid, V(ϕ) = λϕ
4/4!+ βϕ
3/3! (λ>0). The chief physical motivation behind this choice of V(ϕ) corresponds to, apart from its boundedness from below property, the fact that shape wise V(ϕ) has qualitative similarity with standard inflationary classical slow roll potentials. Also, its vacuum expectation value can be negative, suggesting some screening of the inflationary cosmological constant. We choose that ⟨ϕ⟩∼ 0 at early times with respect to the Bunch-Davies vacuum, so that perturbation theory is valid initially. We consider the equations satisfied by ⟨ϕ (t) ⟩ and ⟨ϕ
2(t) ⟩, constructed from the coarse grained equation of motion for the slowly rolling ϕ. We then compute the vacuum diagrammes of various relevant operators using the in-in formalism up to three loop, in terms of the leading powers of the secular logarithms. For a closed fermion loop, we have restricted ourselves here to only the local contribution. These large temporal logarithms are then resummed by constructing suitable non-perturbative equations to compute ⟨ϕ⟩ and ⟨ϕ
2 ⟩. ⟨ϕ⟩ turns out to be at least approximately an order of magnitude less compared to the minimum of the classical potential, -3β/λ, owing to the strong quantum fluctuations. For ⟨ϕ
2 ⟩, we have computed the dynamically generated scalar mass at late times, by taking the appropriate purely local contributions. Variations of these quantities with respect to different couplings have also been presented.
Polarization state transition mechanism of light through turbid media by Monte Carlo simulation
Authors: Ren Yuhu , Jian Jimo , Tan Wenjiang , Wang Jing , Chen Tao , Zhang Haikun , Xia Wei
Published: January 2024

We study the propagation of polarized light through turbid media with high scattering coefficient (μ
s = 50 cm−1) and disclose the physical processes involved in the evolution of Stokes vector. The results show that the components of the Stokes vector can be expressed as the superimposition of the generalized divergence and the generalized curl of the two orthogonal electric field vectors. The components I, Q, and U can be represented as the superimposition of the generalized divergence. The components V can be conveyed as the superimposition of the generalized curl omitting the direction. Further, the depolarization of the linearly polarized light corresponds to the alteration of the generalized divergence, while the depolarization of the circularly polarized light coincides with the variability of the generalized curl omitting the direction. The evolutions of the scattering electric fields arise from the scattering of the particles, followed by the polarization state transition of the incident light and the change of the scattering phase function. Further, the circularly polarized light can preserve the polarization state better than that of the linearly polarized light with an increase of the thickness of the scattering volume.
Phonon transport properties of Janus Pb2
XAs (X = P, Sb, and Bi) monolayers: A DFT study
Authors: Geng 耿 Jiaxin 嘉鑫 , Zhang 张 Pei 培 , Tang 汤 Zhunyun 准韵 , Ouyang 欧 Tao 阳滔
Published: January 2024

Grasping the underlying mechanisms behind the low lattice thermal conductivity of materials is essential for the efficient design and development of high-performance thermoelectric materials and thermal barrier coating materials. In this paper, we present a first-principles calculations of the phonon transport properties of Janus Pb2PAs and Pb2SbAs monolayers. Both materials possess low lattice thermal conductivity, at least two orders of magnitude lower than graphene and h-BN. The room temperature thermal conductivity of Pb2SbAs (0.91 W/mK) is only a quarter of that of Pb2PAs (3.88 W/mK). We analyze in depth the bonding, lattice dynamics, and phonon mode level information of these materials. Ultimately, it is determined that the synergistic effect of low group velocity due to weak bonding and strong phonon anharmonicity is the fundamental cause of the intrinsic low thermal conductivity in these Janus structures. Relative regular residual analysis further indicates that the four-phonon processes are limited in Pb2PAs and Pb2SbAs, and the three-phonon scattering is sufficient to describe their anharmonicity. In this study, the thermal transport properties of Janus Pb2PAs and Pb2SbAs monolayers are illuminated based on fundamental physical mechanisms, and the low lattice thermal conductivity endows them with the potential applications in the field of thermal barriers and thermoelectrics.
Creep deformation of DD15 single crystal superalloy at 980°C/250MPa
Authors: Shi Z X , Liu S Z , Wang X G , Li J R
Published: January 2024

The creep deformation behavior of DD15 alloy was studied under the condition of 980°C/250MPa. The microstructure characteristic and dislocation feature were analyzed after the different creep strain. The creep strain was 0.2%, 0.5%, 1%, 2% and rupture, respectively. The result shows that the creep properties at 980°C/250MPa of DD15 alloy was very good. The first stage creep life was relatively short. When the strain of the alloy was 0.2%, the creep deformation process had already been into the second stage. The second stage creep life was relatively long, which is the majority of the whole life. When the alloy strain was 2%, the creep was in the tertiary stage in which the creep rate increased significantly. The γ′ precipitates were rafted for all the specimens with different strain, and the dimension of raft row in the stress direction slightly grew up as the strain rised. The TCP phase did not precipitated for all samples with different strain. The above results indicate that DD15 alloy has excellent microstructure stability. The dislocation network formed on the two-phase interfaces, and a few dislocations cut into γ′ precipitates in creep specimen deformed with 0.2% strain. With increase of creep strain the dislocation network of sample turned denser.
Effect of secondary orientation on the microstructures in thin-walled castings of nickel-based single-crystal superalloys
Authors: Xu Hanyuan , Huang Taiwen , Zhang Chao , Zhang Jun , Liu Lin
Published: January 2024

With the increasing turbine inlet temperature of aero-engine, the requirement of temperature capacity of turbine blades is more stringent. A variety of complex cooling structures have been designed, among which the micro cooling represented by lamilloy is the latest development. At present, the thickness of lamilloy turbine blade is 0.5 mm or less. The reason for performance degradation caused by thin-walled is still controversial and the understanding of dendrite growth behaviour under space constraints is insufficient. In this study, 0.75 mm wall thickness nickel-based superalloy DD403 samples were cast by high-rate directional solidification. The growth and evolution of dendrites in plank-shaped specimens with different secondary deviation angles were investigated. The variation of dendrite spacing and the arrangement of dendrites under different secondary deviation angles were studied. It is found that the primary dendrite arm spacing in the thin-walled region decreased with the increase of the secondary deviation angle, but there was no significant change in the average size of γ′ phases and elements segregation.
Engineering the flexibility of graphene/h-BN lateral heterojunctions
Authors: Li Yi , Liu Lizhao , Huang Xiaoming
Published: January 2024

Employing the first-principles calculations, the mechanical properties of graphene/hexagonal boron nitride (h-BN) lateral heterojunctions were studied, including the Young’s modulus and bending modulus. It was found that by varying the ratio of graphene in the graphene/h-BN heterojunction, both the Young’s modulus and bending modulus of can be effectively engineered. Particularly, the bending modulus increases with the ratio of graphene to h-BN, providing a way to tailor the flexibility of two-dimensional materials.
Corrosion behavior of X65 steel in gaseous and liquid CO2 transport environments containing multiple impurities and different H2O content
Authors: Yang W J , Zhao X F , Sun C , Xu X X , Sun J B
Published: January 2024

The mechanism of H2O content in different CO2 phase states on the corrosion of pipeline steel was studied by using high-pressure corrosion simulation tests, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and water chemistry simulation calculations. The results show that the corrosion mechanism of X65 steel did not change significantly under different CO2 phase state systems, and the corrosion products were similar. As the H2O content of the system increased, the sulfur-containing products in the corrosion products increased and the degree of corrosion worsened. Additionally, because the aqueous phase formed by the liquid CO2 system contained more corrosive substances, which promote the electrochemical corrosion process of X65 steel, the corrosion degree of X65 steel in a liquid CO2 system was significantly higher than that of X65 steel in a gaseous CO2 system.
Analysis and Suggestions for the Self-blast Problem of Glass Insulators on Transmission Lines
Authors: Zhao Tongkun , Zhang Suhui , Li Jun , Gao Jian
Published: January 2024

By virtue of many advantages such as good self-cleaning ability, outstanding mechanical performance, and excellent anti-vibration-fatigue ability, the glass insulators have been widely used in various alternating-current and direct-current transmission lines. However, the self-blast incidents of glass insulators have frequently occurred in transmission lines with various voltage levels, seriously affecting the safe operation of transmission lines. Herein, the main causes of self-blast problem of glass insulators are summarized and analysed from different perspectives, and some corresponding suggestions have been proposed to reduce the self-blast of glass insulators. In addition, the relevant prospects are provided for the future research work about the glass insulators. The viewpoints in this article have important theoretical and practical significance for improving the safety and reliability of transmission lines and ensuring the stable operation of electrical power systems.
Multi-layered perceptron network for short-term load forecasting
Authors: Tchakala Mouctar , Tafticht Tahar , Rahman Jahidur
Published: January 2024

The use of the multi-layer perceptron (MLP) network for short-term load forecasting is performed. Through weather and load data from the Hydro-Quebec database, capabilities, advantages, and limitations of this artificial intelligence method in load forecasting are investigated. Current management tools for energy systems are based on deterministic optimization methods, where supply, demand, and production are assumed to be known. Changes in electricity supply and demand have made their adjustment more complex. It is no longer a question of adjusting centralized production to demand, but rather of adjusting centralized production, decentralized production, and production from decentralized storage facilities. Our approach will be based on a predictive optimization method adapted to energy systems. An artificial neural network is applied to forecast load for Mascouche in Quebec, Canada. It is about a part of the Hydro-Quebec’s grid where the maximum capacity is 140 megawatts.
A coordinated planning model for power system source-network-load-storage considering multiple types of energy storage
Authors: Sun H , Li Z , Zhang K , Liu M , Yang Y , Liu J
Published: January 2024

Conventional power systems often neglect the amalgamation of planning and scheduling during their preparatory phases, and their methodologies of construction and operation may fall short of the requisites posed by a future characterized by a high proportion of renewable energy integration. In this paper, an integrated planning and scheduling methodology has been developed for the source-network-load-storage power system, factoring in a diverse array of energy storage modalities. Initially, cost models and operational models are formulated encompassing unit retrofitting, line expansion, demand response (DR), energy storage configuration and operation, and penalties related to solar curtailment. Subsequently, the optimization functions and operational constraints of each facet are harmonized, culminating in a comprehensive coordinated planning and scheduling framework for the ‘source-network-load-storage’ power system. The final phase involves simulation analysis conducted on an IEEE-30 nodes power system case. Results illustrate that the integrated ‘source-network-load-storage’ approach exhibits varied efficacies in exploiting system flexibility resources, contingent upon the distinctive capacity-power configurations of multiple types of energy storage. Prudent calibration of energy storage parameters demonstrates the potential to mitigate network underutilization and enhance overall system economics. This corroborates the viability of the proposed ‘integrated planning and scheduling’ model for the power systems.
Trajectory planning of vibration suppression for hybrid structure flexible manipulator based on differential evolution particle swarm optimization algorithm
Authors: Fan Pu , Hu Haidong
Published: January 2024

A differential evolution particle swarm optimization algorithm is proposed to address the vibration problem of a hybrid structure flexible manipulator after motion and stop. Firstly, the errors in the modeling process of the flexible manipulator were corrected, and its state variables were decomposed to establish dynamic and kinematic models. A sliding mode controller was then designed to track the trajectory. To find the optimal trajectory, a mapping function was constructed, and non-uniform interpolation points were selected. A normal distribution function was used to select discrete interpolation points, and the cubic spline interpolation was used to fit the trajectory. To prevent the particle swarm optimization algorithm from falling into local optima, the mutation and crossover operators of the differential evolution algorithm are incorporated into the algorithm, thereby expanding the search range. The effectiveness of this improved method was verified by comparing it with traditional particle swarm optimization algorithms. This study provides a new trajectory planning approach for the motion control of a hybrid structured flexible manipulator and has important practical significance.
Study on the influence of different characterization characteristics on intelligent toilet noise test
Authors: Xu Huayue , Weng Xiaowei , Tao Jiawei , Li Wenjie , Zhan Ni , Li Haiyan
Published: January 2024

With the improvement of the living standards of urban and rural residents, the popularity of intelligent toilets is increasing year by year. The noise issue of intelligent toilets has become one of the main complaints from consumers. The noise of intelligent toilets mainly comes from three functions: cleaning, blowing, and flushing. Due to the lag in research on relevant noise measurement theories and technologies, there is currently a gap in the standards for supporting testing methods. This article adopts step-by-step measurement and overall measurement methods and selects F gear, S gear, and I gear to measure the noise of the tested samples separately. The measurement results of different methods are measured according to L50 and L10, providing a scientific basis for evaluating the noise-influencing factors of intelligent toilet products.
Drill pipe joints fatigue analysis and optimization under special working conditions
Authors: Li Yadong , Nie Minghu , Hu Kaili , Chen Hao , Zhu Zhongxi , Qiao Mu
Published: January 2024

Recently, the number of ultra-deep and extended reach wells has continuously increased. The failure of the drill pipe is prominent when drilling. The thickened area of the drill pipe body and the position of the drill pipe joint often appear fatigued, especially the internal thickening zone for the nonlinear structure of the cast component. Fatigue failure occurred at the drill pipe joint due to non-linear contact between the male and female snaps. The fatigue life S-N curves show that the overall life of drilling with high-resistance torsion drill pipe is increased by 136% compared with API drill pipe, though the maximum stress value was reduced by 8.4%. The high-bend drill pipe has an overall life improvement of 174% over the API drill pipe. High flexural drill pipe reduces stress by 10% compared to the maximum value. At the same time, the drill pipe’s fatigue period and safety factor can be improved by adjusting the drilling speed and annulus pressure properly.
Noise analysis of interior structure under powertrain excitation
Authors: Bai Zhenhe , Wei Jiashuai , Chen Ke
Published: January 2024

To accurately identify the structural noise problem caused by vibration in the cockpit, an experimental study was conducted on a certain type of SUV under uniform acceleration conditions. Based on the planning of the multi-body system dynamics model, a transfer path model with secondary contributions is constructed, and the load is identified using the single degree of freedom model and multi-frequency bandwidth model under the OPAX method based on this path. The results indicate that the second-order vibration of the powertrain is transmitted to the entire suspension system through the X direction of the right suspension. The second-order vibration of the suspension system is then transmitted to the Z direction of the right rear bolt of the subframe, causing the entire subframe vibration and ultimately reaching the target point. This structural path has the greatest impact on the interior noise of the vehicle. This path research method can more accurately determine the main excitation points that cause interior noise problems on a certain path and better understand the overall energy transfer characteristics along the transmission path.
Study of optimization of blade non-uniform allowance process and chatter stability domain
Authors: Wu Yan , Han Shizhan , Chen Xiaoshuai , Xie Yongle
Published: January 2024

In addressing the phenomenon of chatter during the machining of thin-walled components, a machining strategy involving the implementation of a continuous non-uniform toolpath has been proposed as a remedy for chatter suppression. The methodology commences with a meticulous determination of machining allowances, accomplished by utilizing fitting functions. Subsequently, the stiffness coefficients and natural frequencies inherent to the workpiece-tool system are extracted through modal analysis. A stability lobes diagram is formulated, employing the principles of regenerative chatter analysis. This diagram encompasses both uniform toolpath scenarios and non-uniform continuous toolpath scenarios, with the latter established via the least squares method. The resultant stability lobes diagram effectively delineates the boundaries within which chatter remains stable, under varying depths of cut. The stability lobes diagrams substantiate the effectiveness of the non-uniform continuous toolpath constructed via the least squares method in significantly augmenting the inherent stiffness coefficient of the workpiece-tool system, thereby mitigating chatter. This approach serves as a valuable guide for the manufacturing of intricate curved thin-walled components.
Form-finding of tensegrity structures based on genetic algorithm
Authors: Zheng Mingxiang , Du Zhengyin , Li Hui , Lin Min , Ji Zhifei
Published: January 2024

We develop a novel form-finding method that utilizes force density and a genetic algorithm. Firstly, the equilibrium equation is derived by using the force density method. Next, the force density matrix is decomposed through QR decomposition. Subsequently, an optimization objective function is introduced, which incorporates information about the force density values. The optimal solution for the objective function is obtained through the use of a genetic algorithm. We determine a suitable set of force density values that satisfy the requirements of the equilibrium matrix rank deficiency, force density rank deficiency, and precision, thereby establishing the equilibrium configuration of the structure. The simulation results verify the reliability of the proposed method. With its advantages of straightforward calculations, rapid convergence, and high precision, this method proves to be well-suited for the form-finding of both regular and irregular tensegrity structures.
Research on transition corridor of distributed tilting power configuration
Authors: Chen Shengjiu , Yang Youxu , Zhang Xingcui , Wang Bin
Published: January 2024

For a distributed tilt-power configuration aircraft, the transition corridor was studied based on limited conditions such as wing lift characteristics and propeller power requirement. By establishing the dynamic model of each component and balancing according to the balance equation, the boundary of the transition corridor of distributed tilting dynamic configuration is determined. The results show that the minimum forward flight speed required for a low Angle of attack is less than that for a high Angle of attack; the wing lift characteristic high-speed boundary and the propeller power limit boundary together form the high-speed boundary of the transition corridor.
Thermal design of focal plane assembly of wavefront camera for exoplanet imaging corona module
Authors: Wen Chengcheng , Jiang Shu , Xu Mingming , Kong Lingyi , He Jinning
Published: January 2024

The focal plane assembly of wavefront camera is the key imaging device of wavefront detection camera and the key load of the exoplanet imaging coronagraph module. In order to ensure the imaging quality and reduce the dark current and thermal noise, it is necessary to effectively dissipate the heat of the focal plane CCD and other high-power electronic devices to ensure the working performance and reliability of the focal plane assembly. Based on the limited space and cooling resources, this paper adopts the flexible graphene heat conducting cable and grooved heat pipes, and carries out detailed thermal design and thermal analysis of its cooling path. The finite element model is established by thermal analysis software and thermal simulation is carried out. in that steady state, the work temperature range of the CCD chip is -12.8∼-10.9°C, which meets the temperature control index, and the work temperatures of other components are also within the design requirements, which indicate that the thermal design scheme is reasonable and feasible, and meets the task requirements.
Parameter optimization design of an aero-engine bearing chamber based on active learning Kriging
Authors: Qian Yuming , Li Jingkui , Qu Binjie , Liu Zhibin
Published: January 2024

The air-oil two-phase flow in the aero-engine bearing chamber is highly complex and unsteady. To obtain the mapping relationship between the oil volume fraction in the chamber and the oil inlet flow rate and rotational speed for further design optimization, the air-oil two-phase flows are simulated using the level set method in COMSOL Multiphysics software. To avoid frequent calls to the simulation model during the optimization process, which consumes huge computational costs, the Kriging model is applied to approximate the true response of the computational fluid dynamics (CFD) simulations. The point addition process is assisted by introducing the active learning function EI to enhance the efficiency of constructing the Kriging model. Particle swarm optimization (PSO) is applied to optimize the Kriging-based optimization objective function. With the optimal parameters’ combination, the performance of the oil return in the aero-engine bearing chamber is improved. This study has guiding significance for the lubrication design of the aero-engine bearing chamber.
Influence on the roof stability of EMU induced by welding deformation
Authors: Li Yana , Yin Xingfu , Zhang Zeyang
Published: January 2024

The EMU roof with a thin plate structure is prone to buckling deformation during welding, which will affect its stability. Due to the complex structure, large size, and many types of welded joints, it is an urgent problem to solve the influence of different joint shapes on welding deformation and buckling stability in one model. Based on the inherent strain-temperature loading method, the inherent strain data of four kinds of local joint butt, lap, fillet, and plug welding were accurately obtained through joint welding deformation verification. Then the welding deformation simulation and buckling stability analysis were conducted. The results indicate that plug welding will have minimal impact on roof deformation. The roof buckling deformation cannot occur under the original and 1.2 times heat input conditions are selected within the range of the actual given heat source parameters. Under the 1.5 times heat input condition, the roof buckling deformation occurs. The results provide technical support for the selection of the welding process and the roof stability study of the EMU.
Study on the influence of al content on elevated temperature oxidation of MgF2 in HFP/air atmosphere
Authors: Chen Hukui , Jie Yangyang , Chang Li
Published: January 2024

The influence of Al content on the high-temperature oxidation of MgF2 in an air/HFP atmosphere at temperatures ranging from 700 to 1000 °C has been studied with XRD and EDS. The results reveal that the addition of Al accelerated the oxidation of MgF2. With increasing Al content in MgF2, the oxidation of MgF2 was increased. At the same Al content, the oxidation of MgF2 also increased as the temperature rose. These results suggest that the increase of the Al content of MgF2 and the temperature decreased the high-temperature stability of MgF2.