检索结果-南通市图书馆

Determination of Elastoplastic Properties of 2024 Aluminum Alloy Using Deep Learning and Instrumented Nanoindentation Experiment

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2023年第2期36卷 327-339页

作者： mingzhi wang Guitao Zhang Tingguang Liu Weidong wang School of Mechano-Electronic Engineering Xidian UniversityXi’an 710071China CityU-Xidian Joint Laboratory of Micro/Nano Manufacturing Shenzhen 518057China National Center for Materials Service Safety University of Science and Technology BeijingBeijing 100083China

The instrumented nanoindentation technique has been widely used to measure the tensile properties of various materials,for its simple specimen preparation and nearly nondestructive testing *** this paper,a novel inverse method is established for measuring the elastoplastic properties of Al 2024 *** grid indentation experiments are performed on Al 2024 *** obtained experimental load–displacement(P–h)data exhibit obvious scatter *** artificial neural network(ANN)model with tunable hyper-parameters is adopted to establish the forward relationship between elastoplastic parameters and indentation load–displacement *** objective function for quantifying the error norm between predicted and experimental P–h snapshots is *** parameter identification problem is solved using the“interior-point”constraint optimization algorithm..The identified material properties show good agreement with the tensile data,and the error values are−8.66%for elastic modulus,1.08%for yield stress,and 6.90%for hardening *** sensitivity of numerical results to experimental uncertainty is analyzed,and the error bound of experimental data is *** results of sensitivity analysis indicate that the proposed inverse method in the work is very effective and reliable.

关键词： Nanoindentation Material properties Al 2024 alloy Deep learning Parameter identification

Determination of the spin parameter and the inclination angle from the primary and secondary images caused by gravitational lensing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 106-118页

作者： mingzhi wang Songbai Chen Jiliang Jing School of Mathematics and Physics Qingdao University of Science and TechnologyQingdao266061China Institute of Physics and Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou225009China

We study the primary images(PIs)and secondary images(SIs)caused by strong gravitational lensing around a Kerr black hole shadow,which carry some essential signatures related to the black hole *** define a new celestial coordinate,whose origin is the center of the black hole shadow,to locate the PIs and SIs of luminous celestial *** on the dragging effect caused by the rotating black hole and the inclination angle of the observer,the relative positions between the PIs and SIs are different for different values of the Kerr spin parameter a and the observer's inclination angle i;hence,it can be used to determine the values of a and *** propose a specific approach to measure a and i using the PIs and *** time delays between the PIs and SIs are different for different values of a and *** time delays,in conjunction with the relative positions between the PIs and SIs,can enable us to measure a and i more *** PIs and SIs around the black hole shadow act as unique fingerprints for the black hole space-time,using which we can further determine other parameters of different types of compact objects and verify various theories of *** results provide a new method to implement parameter estimation in the study of black hole physics and astrophysics.

关键词： black hole shadow gravitational lensing the primary images the secondary images

Chaotic shadows of black holes:a short review

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2022年第9期74卷 356-369页

作者： mingzhi wang Songbai Chen Jiliang Jing School of Mathematics and Physics Qingdao University of Science and TechnologyQingdaoShandong 266061China Institute of Physics and Department of Physics Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of EducationSynergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangshaHunan 410081China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China

We give a brief review on the formation and the calculation of black hole ***,we introduce the concept of a black hole shadow and the current works on a variety of black hole ***,we present the main methods of calculating photon sphere radius and shadow radius,and then explain how the photon sphere affects the boundary of black hole *** review the analytical calculation for black hole shadows which have analytic expressions for shadow boundary due to the integrable photon motion *** we introduce the fundamental photon orbits which can explain the patterns of black hole shadow ***,we review the numerical calculation of black hole shadows with the backward ray-tracing method and introduce some chaotic black hole shadows with self-similar fractal *** the gravitational waves from the merger of binary black holes have been detected,we introduce a couple of shadows of binary black holes,which all have eyebrowlike shadows around the main shadows with the fractal *** discuss the invariant phase space structures of the photon motion system in black hole space-time,and explain the formation of black hole shadow is dominated by the invariant manifolds of certain Lyapunov orbits near the fixed points.

关键词： black hole shadow photon sphere chaos

Users'experience matter:Delay sensitivity-aware computation offloading in mobile edge computing

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2022年第6期8卷 955-963页

作者： mingzhi wang Tao Wu Tao Ma Xiaochen Fan Mingxing Ke National University of Defense Technology Hefei230031China Consulting Center for Strategic Assessment Academy of Military ScienceBeijing100091China

As a promising computing paradigm,Mobile Edge Computing(MEC)provides communication and computing capability at the edge of the network to address the concerns of massive computation requirements,constrained battery capacity and limited bandwidth of the Internet of Things(IoT)*** existing works on mobile edge task ignores the delay sensitivities,which may lead to the degraded utility of computation offloading and dissatisfied *** this paper,we study the delay sensitivity-aware computation offloading by jointly considering both user's tolerance towards delay of task execution and the network status under computation and communication ***,we use a specific multi-user and multi-server MEC system to define the latency sensitivity of task offloading based on the analysis of delay distribution of task ***,we propose a scoring mechanism to evaluate the sensitivity-dependent utility of task execution and devise a Centralized Iterative Redirection Offloading(CIRO)algorithm to collect all information in the MEC *** starting with an initial offloading strategy,the CIRO algorithm enables IoT devices to cooperate and iteratively redirect task offloading decisions to optimize the offloading strategy until it *** simulation results show that our method can significantly improve the utility of computation offloading in MEC systems and has lower time complexity than existing algorithms.

关键词： Mobile edge computing Computation floading Delay sensitivity Centralized ofloading

Fabrication of onion-like carbon from nanodiamond by annealing

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第12期52卷 3683-3689页

作者： Qin Zou mingzhi wang YanGuo Li YuCheng Zhao LiangHua Zou State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China

Onion-like carbon (OLC) was synthesized by annealing nanodiamond in low vacuum of 1 Pa and at annealing temperatures from 500°C to 1400°C. The high-resolution transmission electron microscope (HRTEM) images, X-ray diffraction (XRD) and Raman spectrum of the OLC showed that there was no OLC when the annealing temperature was lower than 900°C. Moreover, the fragment amorphous carbon existed on the surfaces of the nanodiamond particles. At the annealing temperature of 900°C, the OLC particles began appearing and the size of the OLC particles was smaller than 5 nm. When the annealing temperature was increased from 900°C to 1400°C, the nanodiamond was transformed into OLC gradually. At the annealing temperature of 1400°C, all the nanodiamond particles were transformed into OLC completely. The OLC exhibited similarity to the original nanodiamond particles in shape. A mechanism for the OLC synthesis by annealing was provided. The graphitization started at the surfaces of the nanodiamond particles. The formation process of the OLC includes formation of graphite fragments, connection and curvature of graphite sheets between diamond (111) planes and closure of the graphite layers.

关键词： onion-like carbon(OLC) nanodiamond annealing fabrication

Puerarin partly counteracts the inflammatory response after cerebral ischemia/reperfusion via activating the cholinergic anti-inflammatory pathway

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2013年第34期8卷 3203-3215页

作者： Xiaojie Liu Zhigang Mei Jingping Qian Yongbao Zeng mingzhi wang Medical College of China Three Gorges University

Puerarin, a major isoflavonoid derived from the Chinese medical herb radix puerariae （Gegen）, has been reported to inhibit neuronal apoptosis and play an anti-inflammatory role in focal cerebral ischemia model rats. Recent findings regarding stroke pathophysiology have recognized that anti-inflammation is an important target for the treatment of ischemic stroke. The cholinergic anti-inflammatory pathway is a highly robust neural-immune mechanism for inflammation control. This study was to investigate whether activating the cholinergic anti-inflammatory pathway can be involved in the mechanism of inhibiting the inflammatory response during puerarin-induced cerebral ischemia/reperfusion in rats. Results showed that puerarin pretreatment （intravenous injection） re- duced the ischemic infarct volume, improved neurological deficit after cerebral ischemia/reperfusion and decreased the levels of interleukin-1β, interleukin-6 and tumor necrosis factor-a in brain tissue. Pretreatment with puerarin （intravenous injection） attenuated the inflammatory response in rats, which was accompanied by janus-activated kinase 2 （JAK2） and signal transducers and activators of transcription 3 （STAT3） activation and nuclear factor kappa B （NF-KB） inhibition. These observa- tions were inhibited by the alpha7 nicotinic acetylcholine receptor （a7nAchR） antagonist a-bungarotoxin （a-BGT）. In addition, puerarin pretreatment increased the expression of a7nAchR mRNA in ischemic cerebral tissue. These data demonstrate that puerarin pretreatment strongly protects the brain against cerebral ischemia/reperfusion injury and inhibits the inflammatory re- sponse. Our results also indicated that the anti-inflammatory effect of puerarin may partly be medi- ated through the activation of the cholinergic anti-inflammatory pathway.

关键词： neural regeneration cerebral ischemia/reperfusion inflammation cholinergic anti-inflammatory pathway alpha7 nicotinicacetylcholine receptors nuclear factor kappa B janus-activated kinase 2 signal transducers and activators of transcription 3 grants-supported paper neuroregeneration

Phase structure and hydrogen storage properties of LaMg_(3.70)Ni_(1.18) alloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2011年第5期30卷 458-463页

作者： LI Jinhua LIU Baozhong HAN Shumin HU Lin ZHAO Xin wang mingzhi State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China School of Materials Science and Engineering Henan Polytechnic University Jiaozuo 454000 China College of Environmental and Chemical Engineering Yanshan University Qinhuangdao 066004 China

The phase structure and hydrogen storage properties of LaMg 3.70 Ni 1.18 alloy were investigated. The LaMg 3.70 Ni 1.18 alloy consists of main LaMg 2 Ni phase, minor La 2 Mg 17 and LaMg 3 phases. The alloy can be activated in the first hydriding/dehydriding process, and initial LaMg 2 Ni, La 2 Mg 17 , and LaMg 3 phases transfer to LaH 2.34 , Mg, and Mg 2 Ni phases after activation. The reversible hydrogen storage capacity of the LaMg 3.70 Ni 1.18 alloy is 2.47 wt.% at 558 K, which is higher than that of the LaMg 2 Ni alloy. The pressure-composition-temperature （PCT） curves display two hydriding plateaus, corresponding to the formation of MgH 2 and Mg 2 NiH 4 . However, only one dehydriding plateau is observed, owing to the synergetic effect of hydrogen desorption between MgH 2 and Mg 2 NiH 4 . The uptake time for hydrogen content to reach 99% of saturated state is less than 250 s, and 90% hydrogen can be released in 1200 s in the experimental conditions, showing fast kinetics in hydriding and dehydriding. The activation energies of the LaMg 3.70 Ni 1.18 alloy are –51.5 ± 1.1 kJ/mol and –57.0 ± 0.6 kJ/mol for hydriding and dehydriding, respectively. The hydriding/dehydriding kinetics of the LaMg 3.70 Ni 1.18 alloy is better than that of the Mg 2 Ni alloy, owing to the lower activation energy values.

关键词： hydrogen storage alloys multiphase structure hydrogen storage properties rare earths

A novel non-stoichiometric medium-entropy carbide stabilized by anion vacancies

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第16期47卷 161-166页

作者： Chong Peng Hu Tang Yu He Xiaoqian Lu Peng jia Guoying Liu Yucheng Zhao mingzhi wang State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China Center for High Pressure Science and Technology Advanced Research Beijing 100190China

Recently,high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness,fracture toughness,and ***,as a newly emerging class of materials,the synthesis,performance and applications of high-entropy ceramics are subject to further ***,we reported a new non-stoichiometric TiC0.4/WC/0.5Mo2C medium-entropy carbide(MEC)with a rock-salt *** to the solid solution strengthening and twinning strengthening,the TiCO0.4/WC/0.5Mo2C sintered at 1900℃by spark plasma sintering(SPS)shows superior mechanical behaviors of microhardness(21.7 GPa),which exceeds that expected from the rule of mixture(ROM)of three individual metal carbides(19.1 GPa)and good fracture toughness(5.3 MPa m1/2).Significantly,the bulk synthesized via high-pressure and high-temperature(HPHT)sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness(23.7 GPa)and fracture toughness(6.2 MPa m1/2).In addition,the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC0.4/WC/0.5Mo2C was analyzed via quantitatively calculated *** could significantly enhance the configuratio nal entropy of mixing of the solid *** introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics,especially for multi-component high tempe rature refractory ceramics.

关键词： Anion vacancies Medium-entropy carbide Solid solution strengthening Twinning

Developmental competence and ultrastructural changes of heat-stressed mouse early blastocysts produced in vitro

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2009年第1期55卷 61-66页

作者： Pingping Qu Wenru TIAN Tao LI Zhongling JIANG Shansong GAO Zhongjie TIAN mingzhi wang College of Animal Science ＆ Veterinary Medicine Qingdao Agricultural University Qingdao 266109 Shandong China

Mouse early blastocysts were exposed to temperatures of 39℃ and 41℃ for 2 h, respectively, to determine their developmental competence and ultrastructural changes. The results showed that heat stress at 41 ℃ for 2 h, significantly reduced the percentages of expanded and hatched blastocysts, but not at 39℃ for 2 h. The average cell numbers in expanded blastocysts, which developed from early blastoeysts heat-stressed at temperatures of 39℃ and 41 ℃, were significantly reduced. The average cell numbers in hatched blastocysts subjected to heat stress were no different from those in the control group cultured at 37 ℃ . The mitochondria of the early blastocysts heat-stressed at 39℃ for 2 h, were slightly swollen, but they had recovered after culturing at 37 ℃ for 2 h. However, the mitochondria in the blastocysts heat stressed at 41 ℃ for 2 h were severely swollen, and their number increased. The ribosomes shed from the rough endoplasmic reticulum, and the number of secondary lysosomes in the plasma increased. The integrity of desmosomes was disrupted. The space between the nuclear envelope and the perivitelline membrane enlarged. The fibre fraction and the particulate fraction of nueleoli were separated. The heterochromatin in nueleoli was also increased in its quantity. There were some lamellar-shape structures and heterogeneous dense materials exhibiting in the cytoplasm. The ultrastructural changes induced by heat shock at 41 ℃ for 2 h were not reversible. In conclusion, the damage of heat stress to mitoehondria, lysosomes, ribosomes and cell nucleus, may be one of the most important factors that inhibit the normal development of mouse early blastoeysts .

关键词： Heat tress Mouse Early blastocysts Developmental competence Ultrastructure