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Data-driven analysis of process,structure,and properties of additively manufactured Inconel 718 thin walls

npj Computational Materials 2022年第1期8卷 1168-1182页

作者： Lichao Fang Lin Cheng Jennifer A.Glerum Jennifer Bennett jian cao Gregory J.Wagner Department of Mechanical Engineering Northwestern UniversityEvanstonIL60208USA Department of Materials Science and Engineering Northwestern UniversityEvanstonIL60208USA DMG MORI Hoffman EstatesIL60192USA Department of Mechanical and Materials Engineering Worcester Polytechnic InstituteWorcesterMA01609USA Department of Civil and Mechanical Engineering US Military Acadeemy at West PointWest PointNY10996USA

In additive manufacturing of metal parts,the ability to accurately predict the extremely variable temperature field in detail,and relate it quantitatively to structure and properties,is a key step in predicting part performance and optimizing process *** this work,a finite element simulation of the directed energy deposition(DED)process is used to predict the space-and time-dependent temperature field during the multi-layer build process for Inconel 718 *** thermal model results show good agreement with dynamic infrared images captured in situ during the DED *** relationship between predicted cooling rate,microstructural features,and mechanical properties is examined,and cooling rate alone is found to be insufficient in giving quantitative property *** machine learning offers an efficient way to identify important features from series data,we apply a 1D convolutional neural network data-driven framework to automatically extract the dominant predictive features from simulated temperature *** good predictions of material properties,especially ultimate tensile strength,are obtained using simulated thermal history *** further interpret the convolutional neural network predictions,we visualize the extracted features produced on each convolutional layer and compare the convolutional neural network detected features of thermal histories for high and low ultimate tensile strength cases.A key result is the determination that thermal histories in both high and moderate temperature regimes affect material properties.

关键词： Inconel process additive

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Structure instability forecasting and analysis of giant rock pillars in steeply dipping thick coal seams

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International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1233-1244页

作者： Xing-ping Lai Huan Sun Peng-fei Shan Ming Cai jian-tao cao Feng Cui Energy School Xi’an University of Science and Technology Key Laboratory of Western Mines and Hazard Prevention (Ministry of Education of China) Bharti School of Engineering Laurentian University

Structure stability analysis of rock masses is essential for forecasting catastrophic structure failure in coal seam mining. Steeply dipping thick coal seams （SDTCS） are common in the Urumqi coalfield, and some dynamical hazards such as roof collapse and mining-induced seismicity occur frequently in the coal mines. The cause of these events is mainly structure instability in giant rock pillars sand- wiched between SDTCS. Developing methods to predict these events is important for safe mining in such a complex environment. This study focuses on understanding the structural mechanics model of a giant rock pillar and presents a viewpoint of the stability of a trend sphenoid fractured beam （TSFB）. Some stability index parameters such as failure surface dips were measured, and most dips were observed to be between 46° and 51°. We used a digital panoramic borehole monitoring system to measure the TSFB＇s height （△H）, which varied from 56.37 to 60.50 m. Next, FLAC^3D was used to model the distribution and evolution of vertical displacement in the giant rock pillars; the results confirmed the existence of a TSFB structure. Finally, we investigated the acoustic emission （AE） energy accumulation rate and observed that the rate commonly ranged from 20 to 40 kJ/min. The AE energy accumulation rate could be used to anticipate impeding seismic events related to structure failure. The results presented provide a useful approach for forecasting catastrophic events related to structure instability and for developing hazard prevention technology for mining in SDTCS.

关键词： coal mining structural instability rock pillars forecasting acoustic emission (AE) steeply dipping coal beds

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A review of carbonates as hydrocarbon source rocks: basic geochemistry and oil–gas generation

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Petroleum Science 2019年第4期16卷 713-728页

作者： Liu-Wen Xia jian cao Ming Wang Ju-Lei Mi Ting-Ting Wang MOE Key Laboratory of Surficial Geochemistry School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023JiangsuChina Research Institute of Experiment and Testing PetroChina Xinjiang Oilfield CompanyKaramay 834000XinjiangChina

Carbonates have been known to act as hydrocarbon source rocks, but their basic geochemical and associated hydrocarbon generation characteristics remain not well understood as they occur with argillaceous source rocks in most cases, and the hydrocarbon generation from each rock type is di cult to distinguish, forming one of puzzling issues within the field of petroleum geology and geochemistry. To improve the understanding of this critical issue, this paper reviews recent advances in this field and provides a summary of key areas that can be studied in future. Results show that carbonate source rocks are generally associated with high-salinity environments with low amounts of terrestrial inputs and low dissolved oxygen contents. Petrographically, these source rocks are dark gray or black, fine-grained, stratified, and contain bacterial and algal bioprecursors along with some other impurities. They generally have low organic matter contents, although these can vary significantly in di erent cases(e.g., the total organic carbon contents of marine and lacustrine carbonate source rocks in China are generally 0.1%–1.0% and 0.4%–4.0%, respectively). These rocks contain type I and type II kerogen, meaning there is a lack of vitrinites. This means that assessment of the maturity of the organic matter in these sediments needs to use non-traditional techniques rather than vitrinite reflectance. In terms of molecular geochemistry, carbonate source rocks have typical characteristics indicative of generally reducing and saline environments and lower organism-dominated bioprecursors of organic matter, e.g., high contents of sulfur compounds, low Pr/Ph ratios, and dominance of n-alkanes. Most of the carbonate source rocks are typically dominated by D-type organic facies in an oxidized shallow water mass, although high-quality source rocks generally contain A-and B-type organic facies in saline lacustrine and marine-reducing environments, respectively. The hydrocarbon generation mod

关键词： Saline lacustrine source rocks Carbonates Organic facies Hydrocarbon generation

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Mechanistic data-driven prediction of as-built mechanical properties in metal additive manufacturing

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npj Computational Materials 2021年第1期7卷 767-778页

作者： Xiaoyu Xie Jennifer Bennett Sourav Saha Ye Lu jian cao Wing Kam Liu Zhengtao Gan Department of Mechanical Engineering Northwestern UniversityEvanstonILUSA DMG MORI Hoffman EstatesILUSA Theoretical and Applied Mechanics Northwestern UniversityEvanstonILUSA

Metal additive manufacturing provides remarkable flexibility in geometry and component design,but localized heating/cooling heterogeneity leads to spatial variations of as-built mechanical properties,significantly complicating the materials design *** this end,we develop a mechanistic data-driven framework integrating wavelet transforms and convolutional neural networks to predict location-dependent mechanical properties over fabricated parts based on process-induced temperature sequences,i.e.,thermal *** framework enables multiresolution analysis and importance analysis to reveal dominant mechanistic features underlying the additive manufacturing process,such as critical temperature ranges and fundamental thermal *** systematically compare the developed approach with other machine learning *** results demonstrate that the developed approach achieves reasonably good predictive capability using a small amount of noisy experimental *** provides a concrete foundation for a revolutionary methodology that predicts spatial and temporal evolution of mechanical properties leveraging domain-specific knowledge and cutting-edge machine and deep learning technologies.

关键词： additive properties prediction

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Nanocrystalline La2Mo2O9 and Its Characterization

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Journal of Rare Earths 2004年第z2期22卷 102-106页

作者： Li Qin Xia Tian Li Jiayan Liu Xiangdong Ma Xianfeng Meng jian cao Xueqiang Key Laboratory of Rare Earth Chemistry and Physics Changchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China Key Laboratory of Rare Earth Chemistry and PhysicsChangchun Institute of Applied ChemistryChinese Academy of Sciences.Changchun 130022China

In this work, both the thermal expansion and electrical conductivity of nanocrystalline La2Mo2O9 were *** nanocrystalline powder of La2Mo2O9 was obtained by sol-gel method, and with the help of SHP (superhigh pressure)up to 4.5 × 104 atm at 700 ℃ for a short time, and the nanocrystalline powder was densified without obvious particle size growth. The electrical conductivity of nanocrystalline La2Mo2O9 was one orderof magnitude lower than that of the microcrystalline sample at the same temperature. Owing to the phase transition, the microcrystalline La2Mo2O9 has an abrupt increase of thermal expansion with a peak value of 48 × 10-6 K-1 at 556 ℃. For the nanocrystalline material, the peak value increases to 112 × 10-6 K-1 at 520 ℃. On the other hand, above 600 ℃ the significant growth of particle size of the nanocrystalline La2Mo2O9 was observed, accompanying by a tremendous increase of thermal expansion with a peak value of third higher than that of La2Mo2O9.

关键词： nanocrystalline electrical conductivity lanthanum molybdate superhigh pressure rare earths

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A review of object representation based on local features

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Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第7期14卷 495-504页

作者： jian cao Dian-hui MAO Qiang CAI Hai-sheng LI Jun-ping DU College of Computer and Information Engineering Beijing Technology and Business University School of Computer Science Beijing University of Posts and Telecommunications

Object representation based on local features is a topical subject in the domain of image understanding and computer vision. We discuss the defects of global features in present methods and the advantages of local features in object recognition, and briefly explore state-of-the-art recognition methods using local features, especially the main approaches of local feature extraction and object representation. To clearly explain these methods, the problem of local feature extraction is divided into feature region detection, feature region description, and feature space optimization. The main components and merits of these steps are presented. Technologies for object presentation are classified into three types: vector space, sliding window, and structure relationship models. Future development trends are discussed briefly.

关键词： Object presentation Local feature Image understanding Object recognition Visual words

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Statistical performance of IF estimation of LFM signals with timevarying amplitude using the peak of WVD

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Journal of Systems Engineering and Electronics 2005年第4期16卷 787-791页

作者： Chen Guanghua Ma Shiwei Qin Tinghao Wang jian Li Ming cao Jialin Microelectronic Research & Development Center Shanghai Univ. Shanghai 200072 P. R. China

The instantaneous frequency （IF） estimation of the linear frequency modulated （LFM） signals with time-varying amplitude using the peak of the Wigner-Ville distribution （WVD） is studied. Theoretical analysis shows that the estimation on LFM signals with time-varying amplitude is unbiased, only if WVD of time-varying amplitude reaches its maximum at frequency zero no matter in which time. The statistical performance in the case of additive white Guassian noise is evaluated and an analytical expression for the variance is provided. The simulations using LFM signals with Gaussian envelope testify that IF can be estimated accurately using the peak of WVD for four models of amplitude variation. Furthermore the statistical result of estimation on the signals with amplitude descending before rising is better than that of the signals with constant amplitude when the amplitude variation rate is moderate.

关键词： instantaneous frequency linear frequency modulated signals Wigner-Ville distribution statistical performance variance.

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Targeting matrix metalloproteinases in cancer:Bringing new life to old ideas

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Genes & Diseases 2015年第1期2卷 26-34页

作者： Jillian Cathcart Ashleigh Pulkoski-Gross jian cao Department of Cellular and Molecular Pharmacology Stony Brook UniversityStony BrookNY 11794USA Department of Medicine/Cancer Prevention Stony Brook UniversityStony BrookNY 11794USA

Since the identification of matrix metalloproteinases(MMPs),a family of zincdependent endopeptidases,as being a driving factor for cancer progression and patient prognosis,MMPs have been studied *** early programs targeting MMPs were largely unsuccessful in clinical trials,they remain a viable and highly desirable therapeutic target based on preclinical studies and their role in disease *** information regarding the structure and function of these proteinases is compiled and biotechnology evolves,tools to develop better inhibitors are within our *** methods for high throughput screening and in silico drug design programs have identified compounds which are highly potent,have high binding affinities,and exhibit favorable pharmacokinetic *** recently,advances in drug delivery methods or compounds which bind outside the active site have brought new light to the *** this review,we highlight the role of MMPs in cancer,clinical trials for MMP inhibitors,and novel approaches to targeting MMPs in cancer.

关键词： Cancer Inhibitors Matrix metalloproteinases Metastasis MMPs

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Maternal lysozyme concentrations in the eggs of the Great Cormorant (Phalacrocorax carbo) in relation to breeding density and laying order

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Chinese Birds 2015年第4期6卷 242-245页

作者： jian cao Jirong Li Wen Wang Fang Yang Zhuo Li Laixing Li Key Laboratory of Adaptation and Evolution of Plateau Biota Northwest Institute of Plateau BiologyChinese Academy of Science University of Chinese Academy of Science Sichuan University

Background: Females can differentially deposit the immune factor lysozyme into eggs based on conditions of local breeding density and laying ***: We collected 80 eggs from Great Cormorants(Phalacrocorax carbo) and then analyzed whether the level of lysozymes in the eggs is related to breeding density and laying ***: Between clutches,the level of lysozyme in eggs is positively related to breeding density; while within a clutch,the level of lysozyme is positively related to the laying ***: When parents breed under conditions of high density,they allocate more lysozymes to their offspring,a trait adaptive to the local *** the increase in the level of lysozymes is a function of the laying order seems a necessary condition to mitigate the hierarchy among siblings for improving the survival of the entire clutch.

关键词： Great Cormorant Innate immunity Breeding density Laying order Lysozyme Phalacrocorax carbo Survival

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An axion-like scalar field environment effect on binary black hole merger

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Research in Astronomy and Astrophysics 2018年第6期18卷 35-48页

作者： Qing Yang Li-Wei Ji Bin Hu Zhou-jian cao Rong-Gen Cai Department of Astronomy Beijing Normal University Beijing 100875 China CAS Key Laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing 100049 China

The environment, such as an accretion disk, could modify the signal of the gravitational wave from astrophysical black hole binaries. In this article, we model the matter field around intermediatemass binary black holes by means of an axion-like scalar field and investigate their joint evolution. In detail, we consider equal mass binary black holes surrounded by a shell of axion-like scalar field both in spherically symmetric and non-spherically symmetric cases, and with different strengths of the scalar field. Our result shows that the environmental scalar field could essentially modify the dynamics. Firstly,in the spherically symmetric case, with increase of the scalar field strength, the number of circular orbits for the binary black hole is reduced. This means that the scalar field could significantly accelerate the merger process. Secondly, once the scalar field strength exceeds a certain critical value, the scalar field could collapse into a third black hole with its mass being larger than that of the binary. Consequently,the new black hole that collapses from the environmental scalar field could accrete the binary promptly and the binary collides head-on with each other. In this process, there is almost no quadrupole signal produced, and, consequently, the gravitational wave is greatly suppressed. Thirdly, when the scalar field strength is relatively smaller than the critical value, the black hole orbit could develop eccentricity through accretion of the scalar field. Fourthly, during the initial stage of the inspiral, the gravitational attractive force from the axion-like scalar field could induce a sudden turn in the binary orbits, hence resulting in a transient wiggle in the gravitational waveform. Finally, in the non-spherical case, the scalar field could gravitationally attract the binary moving toward the center of mass for the scalar field and slow down the merger process.

关键词： stars: black holes gravitational waves methods: numerical

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