Mechanical Properties and Energy Absorption of Soft–Hard Dual Phase Lattice Structures Manufactured via Selective Laser Melting

Yi Ren,Yu Nie,Wei Ran,Zhuofan Liu,Lixia Wang,Chao Lou,Wei Chen 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2

Lattice structures with excellent mechanical performance can be achieved through delicate design. In this work, inspired bythe soft–hard multiphase crystals, three types of dual phase lattice structures (DPLS) composed of body-centered cubic withZ-struts (BCCZ) matrix phase and face and body-centered cubic with Z-struts (FBCCZ) reinforcement phase were designedand fabricated by selective laser melting (SLM) using 316L stainless steel powder. Quasi-static compression experimentand numerical simulation were carried out to investigate their mechanical properties, energy absorption and deformationbehavior. The results showed that the mechanical properties of all DPLS samples were higher than that of single phaseBCCZ lattice structure. The four-body diagonal DPLS sample exhibited the highest specific strength and specific stiffness,which was 9.0% and 14.2% higher than single phase BCCZ lattice structure; while, the two-face diagonal DPLS sample hadthe highest specific energy absorption value of 17.45 J/g. Besides, the experimental and simulated results revealed that thearrangements and volume fraction of reinforcement phase had a significant impact on the performance, deformation behaviorand internal stress distribution of the DPLS samples during compressive deformation.

Swin Transformer-based multi-scale crowd localization method

Yi Ren,Xin He 한국차세대컴퓨팅학회 2022 한국차세대컴퓨팅학회 학술대회 Vol.2022 No.10

In this paper, we propose a new framework that enables an object detector trained with only point-level annotations to estimate the centroids and sizes of objects in dense scenes. Specifically, the framework is based on the Swin Transformer structure and introduces a self-designed resolution feature fusion module in the hierarchical structure, where the estimation of object centroids is done directly by point supervision, and the object pseudo-size is initialized based on the assumption of local uniform distribution, and the regression of object size is guided by an improved congestion-aware loss function. In the NWPU-Crowd dataset, our method outperformed the existing state-of-the-art detection counting methods in F1-measure, precision, MSE evaluation criteria.

Present Situations and Future Prospects of Sericulture in China

Yiren, Li Korean Society of Sericultural Science 2000 International Journal of Industrial Entomology Vol.1 No.2

This paper has reviewed the China Sericulture history in the 20th century. On the basis of the current sericulture production, sericulture area distribution, problems and challenges, it has been forecasted that China sericulture will be developed as following points: 1) On a stable basis, cocoon production increased gradually to a suitable amount; 2) Quality cocoon production bases established to form a regionalized, industrialized and specialized sericulture structure; 3) With increase of householding rearing capacities, rearing facilities improved; 4) Production efficiency raised and silk product quality improved through technical innovation; 5) New and diversified products developed from Sericultural resources with new and high technologies.

Irradiation Effects of HT-9 Martensitic Steel

Yiren Chen 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.3

High-Cr martensitic steel HT-9 is one of the candidate materials for advanced nuclear energy systems. Thanks to its excellent thermal conductivity and irradiation resistance, ferritic/martensitic steels such as HT-9 are considered for in-core applications of advanced nuclear reactors. The harsh neutron irradiation environments at the reactor core region pose a unique challenge for structural and cladding materials. Microstructural and microchemical changes resulting from displacement damage are anticipated for structural materials after prolonged neutron exposure. Consequently, various irradiation effects on the service performance of in-core materials need to be understood. In this work, the fundamentals of radiation damage and irradiation effects of the HT-9 martensitic steel are reviewed. The objective of this paper is to provide a background introduction of displacement damage, microstructural evolution, and subsequent effects on mechanical properties of the HT-9martensitic steel under neutron irradiations. Mechanical test results of the irradiated HT-9 steel obtained from previous fast reactor and fusion programs are summarized along with the information of irradiated microstructure. This review can serve as a starting point for additional investigations on the in-core applications of ferritic/martensitic steels in advanced nuclear reactors.

IRRADIATION EFFECTS OF HT-9 MARTENSITIC STEEL

Chen, Yiren Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.3

High-Cr martensitic steel HT-9 is one of the candidate materials for advanced nuclear energy systems. Thanks to its excellent thermal conductivity and irradiation resistance, ferritic/martensitic steels such as HT-9 are considered for in-core applications of advanced nuclear reactors. The harsh neutron irradiation environments at the reactor core region pose a unique challenge for structural and cladding materials. Microstructural and microchemical changes resulting from displacement damage are anticipated for structural materials after prolonged neutron exposure. Consequently, various irradiation effects on the service performance of in-core materials need to be understood. In this work, the fundamentals of radiation damage and irradiation effects of the HT-9 martensitic steel are reviewed. The objective of this paper is to provide a background introduction of displacement damage, microstructural evolution, and subsequent effects on mechanical properties of the HT-9 martensitic steel under neutron irradiations. Mechanical test results of the irradiated HT-9 steel obtained from previous fast reactor and fusion programs are summarized along with the information of irradiated microstructure. This review can serve as a starting point for additional investigations on the in-core applications of ferritic/martensitic steels in advanced nuclear reactors.

First-principles investigations on helium behaviors in oxide-dispersion- strengthened nickel alloys with Hf additions

Wang Yiren,Jia Fan,Jiang Yong 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3

Oxide-dispersion- strengthened nickel alloys with Hf additions are expected to present high temperature mechanical properties and durable helium resistance based on first-principles density functional theory (DFT) calculations. Energetic and charge density evaluations of the helium behaviors were performed in Ni matrix, Y2Hf2O7 oxide and the oxide/matrix interface. With the presence of coherent Y2Hf2O7 in Ni matrix, chances of helium bubbles in Ni can be greatly diminished. The helium atoms shall occupy the interfacial site initially, then diffuse into in the octahedral sites of Y2Hf2O7, and these oxide-captured He atoms prefer to separate individually. Much higher diffusion barrier of He in Y2Hf2O7 than in nickel is related to the strong hybridization between interstitial He-1s and nearest-neighboring O-2p orbitals

Temporal expression profiling of long noncoding RNA and mRNA in the peripheral blood during porcine development

Gu, Yiren,Zhou, Rui,Jin, Long,Tao, Xuan,Zhong, Zhijun,Yang, Xuemei,Liang, Yan,Yang, Yuekui,Wang, Yan,Chen, Xiaohui,Gong, Jianjun,He, Zhiping,Li, Mingzhou,Lv, Xuebin Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.5

Objective: We investigated the temporal expression profiles of long noncoding RNA (lncRNA) and mRNA in the peripheral blood of pigs during development and identified the lncRNAs that are related to the blood-based immune system. Methods: Peripheral blood samples were obtained from the pigs at 0, 7, 28, and 180 days and 2 years of age. RNA sequencing was performed to survey the lncRNA and mRNA transcriptomes in the samples. Short time-series expression miner (STEM) was used to show temporal expression patterns in the mRNAs and lncRNAs. Gene ontology and Kyoto encyclopedia of genes and genomes analyses were performed to assess the genes' biological relevance. To predict the functions of the identified lncRNAs, we extracted mRNAs that were nearby loci and highly correlated with the lncRNAs. Results: In total of 5,946 lncRNA and 12,354 mRNA transcripts were identified among the samples. STEM showed that most lncRNAs and mRNAs had similar temporal expression patterns during development, indicating the expressional correlation and functional relatedness between them. The five stages were divided into two classes: the suckling period and the late developmental stage. Most genes were expressed at low level during the suckling period, but at higher level during the late stages. Expression of several T-cell-related genes increased continuously during the suckling period, indicating that these genes are crucial for establishing the adaptive immune system in piglets at this stage. Notably, lncRNA TCONS-00086451 may promote blood-based immune system development by upregulating nuclear factor of activated T-cells cytoplasmic 2 expression. Conclusion: This study provides a catalog of porcine peripheral blood-related lncRNAs and mRNAs and reveals the characteristics and temporal expression profiles of these lncRNAs and mRNAs during peripheral blood development from the newborn to adult stages in pigs.

3,3′-Diindolylmethane Suppresses Adipogenesis Using AMPKα-Dependent Mechanism in 3T3-L1 Adipocytes and Caenorhabditis elegans

이지혜,Yiren Yue,박연화,이성호 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.7

3,3′-diindolylmethane is a major in vivo metabolite of indole-3-carbinol, a bioactive compound found in cruciferous vegetables. Although 3,3′-diindolylmethane has been implicated to possess antitumorigenic and anti-inflammatory properties, the effect of 3,3′-diindolylmethane on adipogenesis has not been explored previously. Thus, the present study was conducted to determine if 3,3′-diindolylmethane affects adipogenesis using 3T3-L1 adipocytes and Caenorhabditis elegans. Treatment of 3,3′-diindolylmethane significantly reduced fat accumulation without affecting viability in 3T3-L1 adipocytes. 3,3′-diindolylmethane suppressed expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT-enhancer-binding protein α (C/EBPα), fatty acid binding protein 4 (FABP4), and perilipin. In addition, 3,3′-diindolylmethane activated AMP-activated protein kinase α (AMPKα), which subsequently inactivated acetyl CoA carboxylase (ACC), resulting in reduced fat accumulation. These observations were further confirmed in C. elegans as treatment with 3,3′-diindolylmethane significantly reduced body fat accumulation, which was partly associated with aak-1, but not aak-2, orthologs of AMPKα catalytic subunits α1 and α2, respectively. The current results demonstrate that 3,3′-diindolylmethane, a biologically active metabolite of indole-3-carbinol, may prevent adipogenesis through the AMPKα-dependent pathway.

Piceatannol Reduces Fat Accumulation in Caenorhabditis elegans

Peiyi Shen,Yiren Yue,김기홍,박연화 한국식품영양과학회 2017 Journal of medicinal food Vol.20 No.9

Excess fat accumulation and abnormal metabolism are involved in numerous diseases and thus the research on identification of compounds that can regulate energy homeostasis could significantly facilitate the current effort to prevent and/or treat metabolic disorders. Piceatannol, one of the natural stilbenes, was previously found to decrease lipid accumulation of 3T3-L1 adipocytes. However, its role in fat metabolism in vivo is not known. Thus, Caenorhabditis elegans as an animal model was used in the current study to determine the effect of piceatannol on fat accumulation and its underlying mechanisms. The results showed that 50 and 100 μM piceatannol significantly reduced fat accumulation of wild-type worms grown in normal and high-glucose conditions without altering the growth rate, worm length, pumping rate, or moving speed. The current study further indicated that piceatannol decreased the expression of sbp-1 (encodes an ortholog of mammalian sterol regulatory element-binding protein) and its target gene fasn-1 (encodes an ortholog of fatty acid synthase) as well as increased the expression of hosl-1 (encodes an ortholog of hormone-sensitive lipase) in glucose-treated worms. These data suggested that piceatannol reduced fat accumulation in C. elegans by suppression of genes involved in lipid synthesis and possibly through stimulation of lipolysis. Given that piceatannol exerts similar effects in both C. elegans and 3T3-L1 cells, our finding could provide a mechanistic insight into the role of piceatannol in lipid metabolism in mammals.

Dynamic performance of a rotor system with an initial bow and coupling faults of imbalance-rub during whirling motion

Yang Yang,Yiren Yang,Huajiang Ouyang,Xin Li,Dengqing Cao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

The dynamic characteristics of a rotor system with an initial bow and coupling fault of imbalance-rub are investigated in this work. The geometrical nonlinearity of shafts becomes significant due to the large-amplitude whirling motion. Then, the influences of the initial bow and geometrical nonlinearity on the natural frequencies corresponding to the linear part of the rotor system are studied. Moreover, the coupling faults of imbalance-rub are introduced to the rotor system. Complicated nonlinear phenomena are revealed by bifurcation diagrams, time histories, Poincaré sections, and spectra. The influences of several key design parameters, such as initial bow, shaft radius, and casing stiffness, are analyzed. One of the main findings of this investigation is that when initial bow and geometrical nonlinearity coexist in a system, the resonance characteristics are obviously affected by the initial bow’s degree. This coexistence can result in the jump phenomenon, which rapidly increases the amplitude of whirling motion. These findings are useful in the fault diagnosis and feature recognition of rotating machines.