Two kinds of experimental ferritic/martensitic steels (HT-9) with different Si contents were designed for the fourth-generation advanced nuclear reactor cladding material. The effects of Si content ...and tempering temperature on microstructural evolution and mechanical properties of these HT-9 steel were studied. The microstructure of experimental steels after quenching and tempering were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM); the mechanical properties were investigated by means of tensile test, Charpy impact test, and hardness test. The microscopic mechanism of how the microstructural evolution influences mechanical properties was also discussed. Both XRD and TEM results showed that no residual austenite was detected after heat treatment. The results of mechanical tests showed that the yield strength, tensile strength, and plasticity of the experimental steels with 0.42% (% in mass) Si are higher than that with 0.19% Si, whereas hardness and toughness did not change much; when tempered at 760 °C, the strength and hardness of the experimental steels decreased slightly compared with those tempered at 710 °C, whereas plasticity and toughness increased. Further analysis showed that after quenching at 1050 °C for 1 h and tempering at 760 °C for 1.5 h, the comprehensive mechanical properties of the 0.42% Si experimental steel are the best compared with other experimental steels.
In complex product design, lots of time and resources are consumed to choose a preference-based compromise decision from non-inferior preliminary design models with multi-objective conflicts. ...However, since complex products involve intensive multi-domain knowledge, preference is not only a comprehensive representation of objective data and subjective knowledge but also characterized by fuzzy and uncertain. In recent years, enormous challenges are involved in the design process, within the increasing complexity of preference. This article mainly proposes a novel decision-making method based on generalized abductive learning (G-ABL) to achieve autonomous and efficient decision-making driven by data and knowledge collaboratively. The proposed G-ABL framework, containing three cores: classifier, abductive kernel, and abductive machine, supports preference integration from data and fuzzy knowledge. In particular, a subtle improvement is presented for WK-means based on the entropy weight method (EWM) to address the local static weight problem caused by the fixed data preferences as the decision set is locally invariant. Furthermore, fuzzy comprehensive evaluation (FCE) and
Pearson
correlation are adopted to quantify domain knowledge and obtain abducted labels. Multi-objective weighted calculations are utilized only to label and compare solutions in the final decision set. Finally, an engineering application is provided to verify the effectiveness of the proposed method, and the superiority of which is illustrated by comparative analysis.
Mooney viscosity is an important index to reflect the performance and quality of rubber. At present, the rubber Mooney test has the problems of large time delay, destructive and unable to detect ...online, which restricts the development of rubber industry. In this paper, a gas sensor array-based online inspection method for rubber Mooney viscosity is proposed to improve the problems of measurement delay and raw material waste in the traditional method. A multiple generator time series generative adversarial network (MGTSGAN) structure is proposed to address the problem that the lack of sample data volume and uneven data distribution make it difficult to model. Transformer is introduced to solve the problem of traditional generative adversarial networks in dealing with long sequential dependencies. In the experimental part, a rubber Mooney viscosity detection device is built to verify the effectiveness of the proposed method. The performance of different generative models on two gas sensor datasets is compared to verify the advancement and generalization of the proposed method. The experimental results show that the correct rate of this paper’s method for rubber Mooney viscosity classification is higher than 96%. The correct rates are all improved after data enhancement, in which the MGTSGAN proposed in this paper obtains the highest correct rate of 98.35%. For the classification experiments on Gas sensor array under flow modulation dataset also achieved relatively good results. Among them, the highest correct classification rate of 95.63% is achieved after data enhancement using MGTSGAN.
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•Gas sensor array based detection method for rubber mooney viscosity.•Multiple Generator Time Series Generative Adversarial Networks.•Gas sensor array feature mining and classification in data-poor scenarios.
Accurate fault diagnosis and remaining useful life (RUL) prediction are critical for health management before fatal system failures occur. Reasonable stage prediction of RUL can avoid the waste of ...computing power. However, the difficult-to-measure multiple metrics of real systems cause the starting and end point of RUL to be challenging to determine effectively. Based on the data distribution and digital twin technique, this paper proposes a method to collect the steady-state output signal to determine the beginning and end points of the stable equilibrium state system (SET) RUL. The combination of DT technology can accurately reproduce the actual operating state and measurable characteristics of the system, update the component degradation model by collecting the current component parameters in real-time after the starting point of RUL and inject the future parameter state of the component into DT. The DT is equivalent to a multi-indicator acquisition device, which solves the problem of the physical system's difficulty in acquiring multiple indicators determines the remaining life of the system. Achieving a reasonable starting point and accurate endpoint remaining life prediction under the dual constraints of data and mechanism. The Superbuck converter is used as an example for experiments, and the results prove that the method can reasonably determine the system's start and end points to predict the remaining life. The comparison of the three methods proves the superior performance of the method in this paper.
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•A dense CrN layer with excellent oxidation resistance was deposited on Zircaloy.•The steam oxidation mechanism of CrN coating at 1000 ℃ and 1200 ℃ was discussed.•The internal ...oxidation of Zr inside the nitride coating was observed.•The nitrogen diffusion behaviors in CrN coating at high temperature were studied.•A ZrN nano-twins layer formed at the coating/substrate interface after oxidation.
CrN-coated Zircaloy samples were prepared by cathodic arc ion plating, and the microstructure, stability, and oxidation behaviors of the CrN coatings in high-temperature steams were comprehensively investigated. The CrN coating significantly increased the oxidation resistance of Zircaloy exposed to steam through the formation of a dense Cr2O3 oxide layer without cracking or spallation. Two different multi-layered coatings were produced after the steam exposures. The nitrogen diffusion properties of the CrN coatings during oxidation were examined. The internal oxidation of Zr particles inside the nitride coating was observed. A ZrN nano-twinned layer formed at the coating/substrate interface.
Tailplane control system (TCS) is a key component to ensure pitch maneuverability and horizontal stability in flight control. However, due to inherent sealing, time-varying, and uncertainty, ...conventional control methods involve enormous challenges to guarantee optimal operation of the TCS. This article proposes a digital twin-based predictive control method, called twin predictive control (TPC), to explore tailplane optimal control under complex conditions. First, a digital twin of the TCS is established as a predictive model, and twin adaptation is set up to overcome parameter time-varying and uncertainty for supporting accurate prediction. Then, an optimization model is constructed combining tracking error and control adjustment. Based on model transformation, the optimization objective is theoretically proved convex and coupled with the active-set method to enable efficient optimization solving. Finally, the TPC method, integrating the digital twin and the optimization model, is implemented into a physical experimental system to verify the effectiveness of the proposed method. The experimental results and comparisons show that the TPC method can significantly improve tracking and antiinterference performance. Furthermore, it shows merits in excessive adjustment suppression.
•Sn precipitated in Cr2O3 layer after steam oxidation of Cr-coated Zry-4 at 1000 ℃.•The outward diffusion and selective oxidation of Zr in Cr layer were studied.•Larger outward mass flow caused in ...Kirkendall cavities close to Zr/ZrCr2 interface.•Voids formed at oxide/metal interface of coating due to vacancy condensation.•Amorphization of Cr2O3 was observed which due to the decomposition of Cr2O3 grains.
In this study, the steam oxidation behavior of Cr-coated Zry-4 alloy at 1000 °C and the various interesting phenomena observed during the oxidation process were investigated. During oxidation, Sn in the Zry-4 substrate diffused into the coating and precipitated in the Cr2O3 scale. The Kirkendall effect of these Sn-containing precipitates then generated microcavities. Furthermore, the outward diffusion behavior of Zr and the selective oxidation mechanism of the Zr particles were studied. Voids detected at the Cr2O3/Cr interface result mainly from vacancy condensation. The amorphization of Cr2O3 was also observed adjacent to the voids, and the amorphization mechanism was discussed.
•The dense CrAlN and CrAlSiN coatings with Cr interlayer were deposited on the Zircaloy samples by multi-arc ion plating.•The oxidation resistance of Zircaloy samples in high-temperature steam was ...effectively improved by surface coating.•The oxidation behaviors and mechanisms of two types of coatings in 1000 °C and 1200 °C steam were studied and discussed.•The distribution and diffusion behaviors of nitrogen bubbles in two types of coatings during oxidation were studied.•The added silicon in the CrAlSiN coating can improve the corrosion resistance but impact the structural integrity of coating.
CrAlN and CrAlSiN coatings were deposited on Zircaloy samples by multi-arc ion plating (MAIP) and the microstructure, hardness, and oxidation resistance of the two types of coatings in high-temperature steams were investigated. The coatings can effectively protect the substrate from oxidation during exposure in 1000 °C steam for 2 h and can delay the oxidation of substrate for more than 15 min in 1200 °C steam. Mixed oxide layers formed and suppressed the elemental diffusion during oxidation. Nitrogen bubbles were found inside the mixed oxide. The CrAlSiN coatings showed better oxidation resistance but they cracked more easily.
Cr-CrN/TiSiN-Cr multilayer coatings were deposited on Zircaloy substrates by multi-arc ion plating, and the microstructure and oxidation behavior of the as-deposited coatings, specifically the middle ...CrN/TiSiN layer, were investigated. The CrN/TiSiN layer exhibited a superlattice structure. The multilayer coatings effectively protected the Zircaloy substrates from oxidation. (Cr1-xTix)2O3 and Cr2TiO5 phases were produced in the coating after oxidation at 1200 °C for 1500 s. With oxidation time increases, most of the Cr atoms in these two phases were replaced by Ti atoms. Oxidation mechanisms of the as-deposited coatings are discussed and a decomposition model of the superlattice CrN/TiSiN layer is proposed.
•A multilayer coating with middle superlattice CrN/TiSiN layers was prepared.•(Cr1-xTix)2O3, Cr2TiO5, SiO2, and ZrO2 phases generated in coating after oxidation.•The preferential diffusion of Ti caused the decomposition of superlattice layers.•Pores initially formed at oxide/nitride coating interface and then were healed.•Zr in substrate diffused outward to the outer surface of coating and was oxidized.
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