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Nonlinear constitutive models of rock structural plane and their applications

Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 790-806页

作者： Wenlin Feng Shuangjian niu Chunsheng Qiao Dujian Zou School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhenChina Shenzhen Municipal Engineering Corporation Shenzhen518000China School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China

Structural planes play an important role in controlling the stability of rock engineering,and the influence of structural planes should be considered in the design and construction process of rock *** this paper,mechanical properties,constitutive theory,and numerical application of structural plane are studied by a combination method of laboratory tests,theoretical derivation,and program *** test results reveal the change laws of various mechanical parameters under different roughness and normal *** the pre-peak stage,a non-stationary model of shear stiffness is established,and threedimensional empirical prediction models for initial shear stiffness and residual stage roughness are *** nonlinear constitutive models are established based on elasto-plastic mechanics,and the algorithms of the models are developed based on the return mapping *** to a large number of statistical analysis results,empirical prediction models are proposed for model parameters expressed by structural plane characteristic ***,the discrete element method(DEM)is chosen to embed the constitutive models for practical *** running programs of the constitutive models have been compiled into the discrete element model *** comparison results between the proposed model and the Mohr-Coulomb slip model show that the proposed model can better describe nonlinear changes at different stages,and the predicted shear strength,peak strain and shear stiffness are closer to the test *** research results of the paper are conducive to the accurate evaluation of structural plane in rock engineering.

关键词： Structural plane Engineering stability Roughness Normal stress Elasto-plastic constitutive model Discrete element method

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Machine Learning-Based Research on Tensile Strength of SiC-Reinforced Magnesium Matrix Composites via Stir Casting

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 453-466页

作者： Zhihong Zhu Wenhang Ning Xuanyang niu Yuhong Zhao Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering Collaborative Innovation Center of Ministry of Education and Shanxi Province for High-Performance Al/Mg Alloy MaterialsNorth University of ChinaTaiyuan 030051China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China

SiC is the most common reinforcement in magnesium matrix composites,and the tensile strength of SiC-reinforced magnesium matrix composites is closely related to the distribution of *** a uniform distribution of SiC requires fine control over the parameters of SiC and the processing and preparation ***,due to the numerous adjustable parameters,using traditional experimental methods requires a considerable amount of experimentation to obtain a uniformly distributed composite ***,this study adopts a machine learning approach to explore the tensile strength of SiC-reinforced magnesium matrix composites in the mechanical stirring casting *** analyzing the influence of SiC parameters and processing parameters on composite material performance,we have established an effective predictive ***,six different machine learning regression models have been developed to predict the tensile strength of SiC-reinforced magnesium matrix *** validation and comparison,our models demonstrate good accuracy and reliability in predicting the tensile strength of the composite *** research findings indicate that hot extrusion treatment,SiC content,and stirring time have a significant impact on the tensile strength.

关键词： Machine learning Stirring casting Magnesium matrix composite Tensile strength

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Acceptor-engineering tailored type-Ⅰ photosensitizer with aggregation-induced NIR-II emission for cancer multimodal phototheranostics

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Science China Chemistry 2024年第8期67卷 2647-2660页

作者： Jiangao Li niu niu Deliang Wang Xue Liu Yi Qin Lei Wang Ben Zhong Tang Dong Wang Center for AIE Research Shenzhen Key Laboratory of Polymer Science and TechnologyGuangdong Research Center for Interfacial Engineering of Functional MaterialsCollege of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China Guangzhou Municipal and Guangdong Provincial Key Laboratory of Molecular Target Clinical Pharmacologythe State Key Laboratory of Respiratory DiseaseSchool of Pharmaceutical Sciences and the Fifth Affiliated HospitalGuangzhou Medical UniversityGuangzhou 511436China School of Science and Engineering Shenzhen Institute of Aggregate Science and TechnologyThe Chinese University of Hong KongShenzhen(CUHK-Shenzhen)Shenzhen 518172China

Exploration of single molecular species synchronously featured by long excitation/emission wavelength, accurate diagnosis, and effective therapy, remains supremely appealing to implement high-performance cancer phototheranostics. However, those previously established phototheranostic agents are undiversified and stereotyped in terms of structural skeleton, and generally exhibit insufficient phototheranostic outcomes. Herein, we innovatively utilized indanone-condensed thiadiazolo[3,4-g]quinoxaline(ITQ) as electron acceptor to construct novel photosensitizer with second near-infrared(NIR-II) emission. Experimental study and theoretical calculation demonstrated that comparing with the counterparts constituting by widely employed NIR-II building block benzobisthiadiazole(BBTD) and 6,7-diphenylthiadiazoloquinoxaline(DPTQ), ITQ-based photosensitizer(TITQ) showed superior aggregation-induced emission(AIE) characteristics, much stronger type-I reactive oxygen species(ROS) production, and prominent photothermal conversion capacity. Furthermore, TITQ nanoparticles with excellent biocompatibility were capable of effectively accumulating in the tumor site and visualizing tumor through fluorescence-photoacoustic-photothermal trimodal imaging with highly spatiotemporal resolution, and completely eliminating tumor by type-I photodynamic-photothermal therapy.

关键词： phototheranostics aggregation-induced emission NIR-Ⅱfluorescence acceptor engineering photodynamic-photothermal therapy

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Pedicled greater omentum flap for preventing bile leak in liver transplantation patients with poor biliary tract conditions

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Hepatobiliary & Pancreatic Diseases International 2007年第5期6卷 470-473页

作者： Ye, Qi-Fa niu, ying She, Xing-Guo Ming, ying-Zi Cheng, Ke Ma, Yin Ren, Zu-Hai Cent S Univ Xiangya Hosp 3 Res Ctr Natl Hlth Minist Transplantat Med Engn & Technol Changsha 410013 Peoples R China

BACKGROUND: Bile leak remains a main complication in liver transplantation patients with poor biliary tract conditions, mainly caused by an insufficient blood supply or dysplasia of the biliary tract. Although Roux-en-Y modus operandi can be adopted, the risk of other complications of the biliary tract such as infection increases. Using pedicled greater omentum flaps to wrap the anastomotic stoma, which increases the biliary tract blood supply, may reduce the incidence of bile leak. METHODS: Fourteen patients undergoing piggy-back liver transplantation and having poor biliary tract conditions were treated with pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract. Their clinical data were analyzed retrospectively. RESULTS: Of the 14 patients, only one (7.1%) had a mild bile leak on the 8th day post-operation and fully recovered after symptomatic treatment. The other patients had no biliary complications. CONCLUSIONS: Using pedicled greater omentum flaps to wrap the anastomotic stoma of the biliary tract is an effective way to prevent bile leak in liver transplantation patients, especially those with poor biliary tract conditions. However, experience with this surgical technique still needs to be further explored.

关键词： liver transplantation bile leak greater omentum flap

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Highly Thermoconductive,Strong Graphene‑Based Composite Films by Eliminating Nanosheets Wrinkles

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Nano-Micro Letters 2024年第1期16卷 328-340页

作者： Guang Xiao Hao Li Zhizhou Yu Haoting niu Yagang Yao College of Engineering and Applied Sciences Jiangsu Key Laboratory of Artificial Functional Materialsand Collaborative Innovation Center of Advanced MicrostructuresNational Laboratory of Solid State MicrostructuresNanjing UniversityNanjing 210093People’s Republic of China Institute of Laser Manufacturing Henan Academy of SciencesZhengzhou 450052People’s Republic of China Center for Quantum Transport and Thermal Energy Science School of Physics and TechnologyNanjing Normal UniversityNanjing 210023People’s Republic of China

Graphene-based thermally conductive composites have been proposed as effective thermal management materials for cooling high-power electronic ***,when flexible graphene nanosheets are assembled into macroscopic thermally conductive composites,capillary forces induce shrinkage of graphene nanosheets to form wrinkles during solution-based spontaneous drying,which greatly reduces the thermal conductivity of the ***,graphene nanosheets/aramid nanofiber(GNS/ANF)composite films with high thermal conductivity were prepared by in-plane stretching of GNS/ANF composite hydrogel networks with hydrogen bonds andπ-π*** in-plane mechanical stretching eliminates graphene nanosheets wrinkles by suppressing inward shrinkage due to capillary forces during drying and achieves a high in-plane orientation of graphene nanosheets,thereby creating a fast in-plane heat transfer *** composite films(GNS/ANF-60 wt%)with eliminated graphene nanosheets wrinkles showed a significant increase in thermal conductivity(146 W m^(−1)K^(−1))and tensile strength(207 MPa).The combination of these excellent properties enables the GNS/ANF composite films to be effectively used for cooling flexible LED chips and smartphones,showing promising applications in the thermal management of high-power electronic devices.

关键词： Graphene Aramid nanofiber Wrinkles elimination In-plane stretching Thermal conductivity

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Living Chinese Herbal Scaffolds from Microfluidic Bioprinting for Wound Healing

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Research 2024年第1期2023卷 107-118页

作者： Xiaocheng Wang Jinxuan Jia Mengying niu Wenzhao Li Yuanjin Zhao Department of Rheumatology and Immunology Nanjing Drum Tower HospitalSchool of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Oujiang Laboratory(Zhejiang Lab for Regenerative Medicine Vision and Brain Health)Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhouZhejiang 325001China State Key Laboratory of Bioelectronics School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Chemistry and Biomedicine Innovation Center Nanjing UniversityNanjing 210023China

Biological scaffolds have been widely employed in wound healing applications,while their practical efficiency is compromised by insufficient oxygen delivery to the 3-dimensional constructs and inadequate nutrient supply for the long-term healing ***,we present an innovative living Chinese herbal scaffold to provide a sustainable oxygen and nutrient supply for promoting wound *** a facile microfluidic bioprinting strategy,a traditional Chinese herbal medicine(Panax notoginseng saponins[PNS])and a living autotrophic microorganism(microalgae Chlorella pyrenoidosa[MA])were successfully encapsulated into the *** encapsulated PNS could be gradually released from the scaffolds,which promoted cell adhesion,proliferation,migration,and tube formation in *** addition,benefiting from the photosynthetic oxygenation of the alive MA,the obtained scaffolds would produce sustainable oxygen under light illumination,exerting a protective effect against hypoxia-induced cell *** on these features,we have demonstrated through in vivo experiments that these living Chinese herbal scaffolds could efficiently alleviate local hypoxia,enhance angiogenesis,and thereby accelerate wound closure in diabetic mice,indicating their great potential in wound healing and other tissue repair applications.

关键词： healing wound protective

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Adaptive Barrier-Lyapunov-Functions Based Control Scheme of Nonlinear Pure-Feedback Systems with Full State Constraints and Asymptotic Tracking Performance

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Journal of Systems Science & Complexity 2024年第3期37卷 965-984页

作者： niu Ben WANG Xiaoan WANG Xiaomei WANG Xinjun LI Tao Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China School of Mathematics Southeast UniversityNanjing 211189China School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China

In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state *** to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered *** to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be ***,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear *** presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to ***,it is shown that the constraint requirement on the system will not be violated during the ***,two simulation examples are provided to show the effectiveness of the proposed control scheme.

关键词： Asymptotic tracking control barrier Lyapunov functions full state constraints nonlinear pure-feedback systems

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抗氧化损伤因子在胎膜早破未足月儿胎盘中的表达及作用

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中国当代儿科杂志 2022年第1期24卷 71-77页

作者：王大鹏牛颖颖王昕琦金贞爱延边大学附属医院新生儿科吉林延吉133000

目的探讨抗氧化损伤因子核因子E2相关因子2 (nuclear factor erythroid 2-related factor 2,Nrf2)、血红素氧合酶1 (heme oxygenase-1, HO-1)及NAD(P)H:醌氧化还原酶1 [NAD(P)H:quinone oxidoreductase-1,NQO1]与未足月胎膜早破的相关性。方法前瞻性选取2019~2020年在延边医院住院的新生儿为研究对象,其中未足月胎膜早破新生儿30例,足月胎膜早破新生儿32例,足月无胎膜早破新生儿35例。应用苏木精-伊红染色法观察三组胎盘组织炎症变化。采用免疫组织化学染色法检测Nrf2、HO-1及NQO1在胎盘组织中的表达。应用Western blot法检测胎盘组织中Nrf2、HO-1及NQO1的蛋白表达水平。结果足月胎膜早破组和足月无胎膜早破组胎盘组织中Nrf2、HO-1及NQO1的阳性表达率及蛋白相对表达量均高于未足月胎膜早破组(P0.05)。结论胎盘组织中Nrf2、HO-1及NQO1的低水平表达可能与未足月胎膜早破有关,提示抗氧化损伤是预防未足月胎膜早破的方向之一。[中国当代儿科杂志,2022,24 (1):71-77]

关键词：未足月胎膜早破氧化应激核因子E2相关因子2 血红素氧合酶1 NAD(P)H:醌氧化还原酶1 新生儿

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刀具前角对超声复合加工成形切屑组织与性能的影响

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材料导报 2023年第17期37卷 225-231页

作者：孙海猛牛赢焦锋王壮飞河南理工大学机械与动力工程学院河南焦作454003 西峡县内燃机进排气管有限责任公司河南南阳474500

超细晶纯铜作为重要的基础材料和功能材料成为当前金属材料的研究热点,本工作在大应变挤压-切削法(Large strain extrusion machining,LSEM)的基础上提出超声复合切削法(Ultrasonic compound cutting,UCC)来制备超细晶纯铜。超声复合切... 详细信息

超细晶纯铜作为重要的基础材料和功能材料成为当前金属材料的研究热点,本工作在大应变挤压-切削法(Large strain extrusion machining,LSEM)的基础上提出超声复合切削法(Ultrasonic compound cutting,UCC)来制备超细晶纯铜。超声复合切削中刀具前角是影响切屑应变、晶粒尺寸、位错密度及性能的关键要素,为了研究刀具前角对纯铜切屑组织和性能的影响,基于ABAQUS软件建立超声复合切削三维有限元模型,分析切削变形区等效应变、等效应变率和切削温度的变化;设计单因素试验,分析刀具前角和超声振动对切屑微观组织、位错密度和显微硬度的影响。结果表明:随着刀具前角的增加,等效应变和切削温度逐渐减小,等效应变率会先增大后减小。与LSEM切屑相比,加入超声振动后切屑晶粒细化程度和位错密度均提高,硬度增加5%。当刀具前角为30°时,切屑晶粒由粗晶细化至亚微米级拉长晶,宏观硬度从基体的92.5HV提高至131.8HV;当刀具前角为15°时,晶粒进一步细化为等轴细晶,位错密度为1.14×10^(13)m^(-2),硬度提高至184.3HV,此时纯铜切屑的硬度符合Hall-Petch关系。

关键词：刀具前角超声复合切削法微观组织位错密度硬度

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Blockchain-Based Key Management Scheme Using Rational Secret Sharing

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Computers, Materials & Continua 2024年第4期79卷 307-328页

作者： Xingfan Zhao Changgen Peng Weijie Tan Kun niu State Key Laboratory of Public Big Data College of Computer Science and TechnologyGuizhou UniversityGuiyang550025China Guizhou Big Data Academy Guizhou UniversityGuiyang550025China

Traditional blockchain key management schemes store private keys in the same location,which can easily lead to security issues such as a single point of ***,decentralized threshold key management schemes have become a research focus for blockchain private key *** security of private keys for blockchain user wallet is highly related to user identity authentication and digital asset *** threshold blockchain private key management schemes based on verifiable secret sharing have made some progress,but these schemes do not consider participants’self-interested behavior,and require trusted nodes to keep private key fragments,resulting in a narrow application scope and low deployment efficiency,which cannot meet the needs of personal wallet private key escrow and recovery in public *** design a private key management scheme based on rational secret sharing that considers the self-interest of participants in secret sharing protocols,and constrains the behavior of rational participants through reasonable mechanism design,making it more suitable in distributed scenarios such as the public *** proposed scheme achieves the escrow and recovery of personal wallet private keys without the participation of trusted nodes,and simulate its implementation on smart *** to other existing threshold wallet solutions and keymanagement schemes based on password-protected secret sharing(PPSS),the proposed scheme has a wide range of applications,verifiable private key recovery,low communication overhead,higher computational efficiency when users perform one-time multi-key escrow,no need for trusted nodes,and personal rational constraints and anti-collusion attack capabilities.

关键词： Blockchain smart contract rational secret sharing key management

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