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Synergistic strengthening mechanism of gradient structure AZ31 magnesium alloy plate in hard plate rolling

Progress in Natural Science:Materials International 2023年第5期33卷 652-659页

作者： wen tao niu Feng Li Jia Yang Zhang Chao Li Lu Sun School of Materials Science and Chemical Engineering Harbin University of Science and Technology Key Laboratory of Advanced Manufacturing and Intelligent Technology Ministry of Education Harbin University of Science and Technology Heilongjiang Provincial Key Laboratory of Light Metal Materials Modification & Green Forming Technology Harbin University of Science and Technology

Compared with homogeneous structural materials, gradient structural materials are easier to realize the strengthductility optimization. Research on the strengthening mechanism of different gradient structure materials is a meaningful way to broaden the application of gradient structure materials. In this paper, the AZ31 magnesium alloy plate was rolled by hard plate rolling. The gradient structure was controlled by changing the initial plate thickness. When the initial plate thickness was 4 mm, AZ31 magnesium alloy shows excellent strength and ductility, the tensile strength was 282.2 MPa, and the ductility was 28.4 %. The change of the initial plate thickness changes the stress state which forming a gradient structure with different characteristic layers. The extra strengthening between different characteristic layers improves the properties of gradient structure, which makes the magnesium alloy change from a uniaxial stress state to a multi-axial stress state during the tensile process. The increase of the characteristic layer induces more geometrically necessary dislocation accumulation, improving the gradient structure’s strength and ductility. This research provides a new design strategy for the forming and performance optimization of gradient structure magnesium alloy plate by hard plate rolling, which has good industrial production and application potential.

关键词： Hard plate rolling Gradient structure AZ31 magnesium alloy Extra strengthening Geometrically necessary dislocation

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Microstructure Characteristics and Corrugation Interface Behavior of Al/Mg/Al Composite Plate Rolled Under Large Strain

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Acta Metallurgica Sinica(English Letters) 2023年第5期36卷 827-838页

作者： Peng-Da Huo Feng Li wen-tao niu Rong-He Gao&An-Xin Zhang School of Materials Science and Chemical Engineering Harbin University of Science and TechnologyHarbin150040China Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education Harbin Institute of TechnologyHarbin150001China Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationHarbin Engineering UniversityHarbin150001China

Traditional rolled(TR)aluminum(Al)/magnesium(Mg)/aluminum(Al)composite plates have many bottlenecks such as multiple passes,low interlaminar strength,and weak mechanical *** this paper,the hard-plate rolling(HPR)method was used to prepare Al/Mg/Al composite plates under a single pass reduction of 60%.The results show that the ultimate tensile strength(UTS)of the composite plate obtained by hard-plate rolling is 262.3 MPa,and the percentage of total elongation at fracture(At)is 12.3%,which is 31.6%and 37.4%higher than that of the traditional rolling,*** is attributed to the unique corrugated interlocking structure of the interface of the composite plate caused by hard-plate *** shear texture produced by the Mg plate weakens the strong-basal *** the same time,the strong basal slip and the large amount of energy stored in the deformed grains provide favorable conditions for dynamic recrystallized(DRX)*** microstructure is deeply refined by DRX,and the strength and plasticity of the composite plate are improved *** provides scientific guidance for the development of high-performance lightweight composite plates and the research on hard-plate rolling technology and also has good industrial production and application potential.

关键词： Hard-plate rolling Al/Mg/Al composite plate Corrugated interface Strength-plasticity Strengthening mechanism

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Vascularization ability of glioma stem cells in different three-dimensional microenvironments

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Regenerative Biomaterials 2024年第1期3卷 34-43页

作者： Xuanzhi Wang tao Xu Chaoshi niu Department of Neurosurgery The First Affliated Hospital of USTCDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiAnhui230036China Department of Neurosurgery Sichuan Provincial People's HospitalUniversity of Electronic Science and Technology of ChinaChengdu 610072People's Republic of China Center for Bio-intelligent Manufacturing and Living Matter Bioprinting Research Institute of Tsinghua University in ShenzhenTsinghua UniversityShenzhen 518057People's Republicof China

Glioblastoma(GBM)is among the most common and aggressive adult central nervous system *** prominent charac-teristic of GBM is the presence of abnormal microvessels.A significant correlation between angiogenesis and prognosis has been *** reconstructing this neovascula-rization and tumor microenvironment through personalized in vitro disease models presents a significant ***,it is crucial to develop new anti-angiogenic therapies for *** this study,3D bioprinted glioma stem cell(GSC)-laden hydrogel scaffolds,hybrid Gsc hydrogels and ceil-free hydrogel scaffolds were manufactured to investigate the vas-cularization ability of GsCs in varying 3D microenvironments.

关键词： 3D bioprinting xenograft tumors GSC-laden hydrogel scaffold glioblastoma angiogenesis

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Modeling tuberous sclerosis complex with human induced pluripotent stem cells

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World Journal of Pediatrics 2024年第3期20卷 208-218页

作者： Weibo niu Benjamin Siciliano Zhexing wen Department of Psychiatry and Behavioral Sciences Emory University School of MedicineWhitehead Research Building 447615 Michael StreetAtlantaGA 30322USA The Graduate Program in Molecular and Systems Pharmacology Laney Graduate SchoolEmory UniversityAtlanta.GA 30322.USA Department of Cell Biology Emory University School of MedicineWhitehead Research Building 447615 Michael StreetAtlantaGA30322USA Department of Neurology Emory University School of MedicineWhitehead Research Building 447.615 Michael StreetAtlantaGA 30322USA

Background Tuberous sclerosis complex(TSC)is an autosomal dominant genetic disorder with a birth incidence of I:6000 in the United States that is characterized by the growth of non-cancerous tumors in multiple organ systems including the brain,kidneys,lungs,and ***,TSCis also associated with signicant neurological manifestations including epilepsy TSC-associated neuropsychiatric disorders,intellectual disabilities,and autism spectrum *** in the TSCI or TSC2 genes are well-established causes of TSC,which lead to TSC1/TSC2 deficiency in organs and hyper-activation of the mammalian target of rapamycin signaling *** models have been widely used to study the effect of TSCl/2 genes on the development and function of the *** considerable progress in understanding the molecular mechanisms underlying TSC in animal models,a human-specific model is urgently needed to investigate the effects of TSCl/2 mutations that are unique to human *** sources Literature reviews and research articles were published in PubMed-indexed *** Human-induced pluripotent stem cells(iPSCs),which capture risk alleles that are identical to their donors and have the capacity to differentiate into virtually any cell type in the human body,pave the way for the empirical study of previously inaccessible biological systems such as the developing human *** In this review,we present an overview of the recent progress in modeling TSC with human iPSC models,the existing limitations,and potential directions for future research.

关键词： Induced pluripotent stem cells Three-dimensional cultures Tuberous sclerosis complex Two-dimensional cultures

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The Multi-parameter Test of Gravitational Wave Dispersion with Principal Component Analysis

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Research in Astronomy and Astrophysics 2024年第5期24卷 140-150页

作者： Zhi-Chu Ma Rui niu wen Zhao CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

In this work, we consider a conventional test of gravitational wave(GW) propagation which is based on the phenomenological parameterized dispersion relation to describe potential departures from General Relativity(GR)along the propagation of GWs. But different from tests conventionally performed previously, we vary multiple deformation coefficients simultaneously and employ the principal component analysis(PCA) method to remedy the strong degeneracy among deformation coefficients and obtain informative posteriors. The dominant PCA components can be better measured and constrained, and thus are expected to be more sensitive to potential departures from the waveform model. Using this method we analyze ten selected events and get the result that the combined posteriors of the dominant PCA parameters are consistent with GR within 99.7% credible intervals. The standard deviation of the first dominant PCA parameter is three times smaller than that of the original dispersion parameter of the leading order. However, the multi-parameter test with PCA is more sensitive to not only potential deviations from GR but also systematic errors of waveform models. The difference in results obtained by using different waveform templates hints that the demands of waveform accuracy are higher to perform the multiparameter test with PCA. Whereas, it cannot be strictly proven that the deviation is indeed and only induced by systematic errors. It requires more thorough research in the future to exclude other possible reasons in parameter estimation and data processing.

关键词： gravitational waves-gravitation-black hole physics

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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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The Influence of the Sun and Moon on the Observation of Very High Energy Gamma-ray Sources Using EAS Arrays

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Research in Astronomy and Astrophysics 2024年第6期24卷 245-252页

作者： tao wen Songzhan Chen Benzhong Dai School of Physics and Astronomy Yunnan UniversityKunming 650091China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Tianfu Cosmic Ray Research Center Chengdu 610000China

With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the ***,the Sun and Moon would have some impacts on the observation of gamma-ray sources,which have not been taken into account in previous *** this paper,the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is *** tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some *** absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are *** main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray *** influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.

关键词： astroparticle physics Sun:general methods:observational Sun:UV radiation

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Study on a conical bearing for acceleration-sensitive equipment

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 103-128页

作者： Pang Hui Xu wen Dai Junwu Jiang tao Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China School of Civil Engineering and Transportation Beihua UniversityJilin 132013China

Seismic isolation effectively reduces seismic demands on building structures by isolating the superstructure from ground vibrations during ***,isolation strategies give less attention to acceleration-sensitive systems or ***,as the isolation layer’s displacement grows,the stiffness and frequency of traditional rolling and sliding isolation bearings increases,potentially causing self-centering and resonance *** a result,a new conical pendulum bearing has been selected for acceleration-sensitive equipment to increase self-centering capacity,and additional viscous dampers are incorporated to enhance system ***,the theoretical formula for conical pendulum bearings is supplied to analyze the device’s dynamic parameters,and shake table experiments are used to determine the proposed device’s isolation efficiency under various *** to the test results,the newly proposed devices have remarkable isolation performance in terms of minimizing both acceleration and displacement ***,a numerical model of the isolation system is provided for further research,and the accuracy is demonstrated by the aforementioned experiments.

关键词： seismic isolation acceleration-sensitive equipment the conical pendulum bearing shake table tests isolation performance,numerical model

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UAV-assisted cooperative offloading energy efficiency system for mobile edge computing

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Digital Communications and Networks 2024年第1期10卷 16-24页

作者： Xue-Yong Yu wen-Jin niu Ye Zhu Hong-Bo Zhu Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and Telecommunications Nanjing210003China Engineering Research Centerof Health Service System Based on Ubiquitous Wireless Networks Ministry of EducationNanjng Universityof Posts and Telecommunications Nanjing210003China

Reliable communication and intensive computing power cannot be provided effectively by temporary hot spots in disaster areas and complex terrain ground *** this has greatly developed the application and integration of UAV and Mobile Edge Computing(MEC)to the Internet of Things(loT).However,problems such as multi-user and huge data flow in large areas,which contradict the reality that a single UAV is constrained by limited computing power,still *** to allowing UAV collaboration to accomplish complex tasks,cooperative task offloading between multiple UAVs must meet the interdependence of tasks and realize parallel processing,which reduces the computing power consumption and endurance pressure of *** the computing requirements of the user terminal,delay constraint of a computing task,energy constraint,and safe distance of UAV,we constructed a UAV-Assisted cooperative offloading energy efficiency system for mobile edge computing to minimize user terminal energy ***,the resulting optimization problem is originally nonconvex and thus,difficult to solve *** tackle this problem,we developed an energy efficiency optimization algorithm using Block Coordinate Descent(BCD)that decomposes the problem into three convex ***,we jointly optimized the number of local computing tasks,number of computing offloaded tasks,trajectories of UAV,and offloading matching relationship between multi-UAVs and multiuser *** results show that the proposed approach is suitable for different channel conditions and significantly saves the user terminal energy consumption compared with other benchmark schemes.

关键词： Computation offloading Internet of things(IoT) Mobile edge computing(MEC) Block coordinate descent(BCD)

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In situ embedded bismuth nanoparticles among highly porous carbon fibers for efficient carbon dioxide reduction

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Rare Metals 2024年第9期43卷 4312-4320页

作者： Wei-Jian Guo Ao Zhou wen-wen Cai Jin-tao Zhang Key Laboratory for Colloid and Interface Chemistry (Ministry of Education) School of Chemistry and Chemical EngineeringShandong University

Electrocatalysis provides an optimal approach for the conversion of carbon dioxide(CO2) into high-value chemicals, thereby presenting a promising avenue toward achieve carbon neutrality. However, addressing the selectivity and stability challenges of metal catalysts in electrolytic reduction remains a daunting task. In this study, the electrospinning method is employed to fabricate porous carbon nanofibers loaded with bismuth nanoparticles with the help of in situ pyrolysis. The porous carbon nanofibers as conductive support would facilitate the dispersion of bismuth active sites while inhibiting their aggregation and promoting the mass transfer, thus enhancing their electrocatalytic activity and stability. Additionally, nitrogen doping induces electron delocalization in bismuth atoms through metal-support interactions, thus enabling efficient adsorption of intermediates for improving selectivity based on the theoretical calculation. Consequently, Bi@PCNF-500 exhibits the exceptional selectivity and stability across a wide range of potential windows. Notably, its faradaic efficiency(FE) of formate reaches 92.7% in H-cell and94.9% in flow cell, respectively, with good electrocatalytic stability. The in situ characterization and theoretical calculations elucidate the plausible reaction mechanism to obtain basic rules for designing efficient electrocatalyst.

关键词： Carbon dioxide reduction Electron delocalization N-doping Porous carbon nanofiber

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