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Ultrahigh hardness of carbon steel surface realized by novel solid carburizing with rapid diffusion of carbon nanostructures

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Journal of Materials Science & Technology 2017年第10期33卷 1210-1218页

作者： Qing Tao jian Wang Liming Fu zheng Chen Chengjin Shen Dekun Zhang zhi Sun School of Materials Science and Engineering China University of Mining and Technology School of Materials Science and Engineering Shanghai Jiao Tong University

In this study, a novel rapid solid carburizing process with a large diffusion depth using nano-diamonds（NDs） was conducted for low carbon steel. Changes of annealed NDs were obtained by Raman spectroscopy and transmission electron microscopy（TEM）, and the results suggested that the NDs experience a stripping process before a special solid-reaction with surface iron atoms from steel substrate. Onionlike carbon（OLC） derived from the annealed NDs provided broken graphitic ribbons as carbon sources that accelerated the rate of adsorption and diffusion. Examination of the surface layer at equilibrium using TEM and X-ray photoelectron spectroscopy（XPS） also revealed the special state of carbon, and an ultrafine mixed phase microstructure was obtained by rapid solid-phase transformation. As a result, a surface hardened layer with ultrahigh hardness and a smooth transition region were realized. We believe that these kinds of diamond or graphitic structures with high activity states have an important influence not only on adsorption and diffusion but also on this special solid-phase transformation.

关键词： Solid carburizing Onion-like carbon(OLC) Diffusion Solid-phase transformation Ultrahigh hardness

Aerobic degradation of methyl tert-butyl ether by a Proteobacteria strain in a closed culture system

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Journal of Environmental Sciences 2007年第1期19卷 18-22页

作者： ZHONG Wei-hong CHEN jian-meng LU zheng CHEN Dong-zhi CHEN Xiao College of Biological and Environmental Engineering Zhefiang University of Technology Hangzhou 310032 China

The contamination of methyl ten-butyl ether （MTBE） in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PMI, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen （DO） levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tea-butyl alcohol, isopronol and acetone were the main intermediate products.

关键词： methyl tert-butyl ether biodegradation β-Proteobacteria intermediate products

Role of SPECT/CT in diagnosis of hepatic hemangiomas

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World Journal of Gastroenterology 2005年第34期11卷 5336-5341页

作者： jian-Guo zheng zhi-Ming Yao Chong-YeShu Ying Zhang Xia Zhang Department of Nuclear Medicine Beijing Hospital Beijing 100730 China Imaging Center Central Hospital of Siping CitySiping 136000 Jilin Province China Department of Nuclear Medicine People's Hospitalin Liaocheng City Liaocheng 252000 Shandong Province China Department of Anesthesiology West China HospitalSichuan University Chengdu 610041 Sichuan Province China

AIM: To investigate the role of SPECT/CT in the diagnosis of hepatic hemangiomas whose anatomical positions are not ideal, situated adjacent to the heart, the inferior cava,hepatic vessels or abdominal aorta, ***: The hepatic perfusion, blood pool, and fusion imaging were carried out using SPECT/CT in 54 patients,who were suspected for hepatic hemangiomas. When the anatomical positions were not ideal, the diagnosis was difficult by SPECT only. So the information of computed tomography (CT) was applied to help in diagnosing. The results were recorded as hemangiomas or ***: Of the 54 patients, 31 patients were diagnosed as suffering from hepatic hemangiomas. The anatomical positions of eight patients' hepatic hemangiomas (25.81%)were not ideal. Among these lesions of the eight patients,three patients' hepatic lesions were located near to the abdominal aorta, one to the heart, and four to the inferior cava. In addition, six abnormal radioactivity accumulation regions, adjacent to the heart and inferior cava, with the help of CT, were confirmed to be the imaging of inferior cava other than hepatic ***: When the anatomical positions of hepatic hemangiomas are not good enough for diagnosis, the fusion imaging of SPECT/CT is a simple and efficient method for differential diagnosis.

关键词： SPECT/CT Hepatic hemangiomas Scintigraphy

Pulsar candidate classification with deep convolutional neural networks

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Research in Astronomy and Astrophysics 2019年第9期19卷 119-128页

作者： Yuan-Chao Wang Ming-Tao Li zhi-Chen Pan jian-Hua zheng National Space Science Center Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China National Astronomical Observatories Chinese Academy of SciencesBeijing100101China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing100101China

As the performance of dedicated facilities has continually improved, large numbers of pulsar candidates are being received, which makes selecting valuable pulsar signals from the candidates challenging. In this paper, we describe the design for a deep convolutional neural network(CNN) with 11 layers for classifying pulsar candidates. Compared to artificially designed features, the CNN chooses the subintegrations plot and sub-bands plot for each candidate as inputs without carrying biases. To address the imbalance problem, a data augmentation method based on synthetic minority samples is proposed according to the characteristics of pulsars. The maximum pulses of pulsar candidates were first translated to the same position, and then new samples were generated by adding up multiple subplots of pulsars. The data augmentation method is simple and effective for obtaining varied and representative samples which keep pulsar characteristics. In experiments on the HTRU 1 dataset, it is shown that this model can achieve recall of 0.962 and precision of 0.963.

关键词： pulsars:general methods:statistical methods:data analysis

INDO　Studies　on　the　Electronic　Structure　of(2,4-C₇H₁₁)₂Yb（DME）

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Chemical Research in Chinese Universities 1998年第1期14卷 59-64页

作者： Feng, jian-nan Wang, zhi-zhong Zhang, So-bo Liu, Ju-zheng Jilin Univ Inst Theoret Chem Changchun 130023 Peoples R China Jilin Univ Dept Chem Changchun 130023 Peoples R China

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ＩＮＤＯＳｔｕｄｉｅｓｏｎｔｈｅＥｌｅｃｔｒｏｎｉｃｓＳｔｒｕｃｔｕｒｅｏｆ（２，４－Ｃ７Ｈ１１）２Ｙｂ（ＤＭＥ）ＦＥＮＧＪｉａｎ－ｎａｎ，ＷＡＮＧＺｈｉ－ｚｈｏｎｇ，ＺＨＡＮＧＳｏ－ｂｏ，ＬＩＵＪｕ－ｚｈｅｎｇ（ＩｎｓｔｉｔｕｔｅｏｆＴｈｅｏｒｅｔ...

关键词： INDO Studies Electronic the Structure DME C7H Yb

A new data normalization method for unsupervised anomaly intrusion detection

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第10期11卷 778-784页

作者： Long-zheng CAI jian CHEN Yun KE Yao CHEN zhi-gang LI Engineering and Commerce College South-Central University for Nationalities Wuhan 430065 China Guangdong Institute of Science and Technology Zhuhai 519090 China

Unsupervised anomaly detection can detect attacks without the need for clean or labeled training *** paper studies the application of clustering to unsupervised anomaly detection(ACUAD).Data records are mapped to a feature *** are detected by determining which points lie in the sparse regions of the feature space.A critical element for this method to be effective is the definition of the distance function between data *** propose a unified normalization distance framework for records with numeric and nominal features mixed data.A heuristic method that computes the distance for nominal features is proposed,taking advantage of an important characteristic of nominal features-their probability ***,robust methods are proposed for mapping numeric features and computing their distance,these being able to tolerate the impact of the value difference in scale and diversification among features,and outliers introduced by *** experiments with the KDD 1999 dataset showed that ACUAD can detect intrusions with relatively low false alarm rates compared with other approaches.

关键词： Unsupervised anomaly detection Data mining Intrusion detection Network security

Effects of frustration on explosive synchronization

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Frontiers of physics 2016年第6期11卷 67-74页

作者： Xia Huang jian Gao Yu-Ting Sun zhi-Gang zheng Can Xu Department of Mathematics and Physics North China Electric Power University Beijing 102206 China Department of Physics and the Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems (Beijing) Beijing Normal University Beijing 100875 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

In this study, we consider the emergence of explosive synchronization in scale-free networks by considering the Kuramoto model of coupled phase oscillators. The natural frequencies of oscillators are assumed to be correlated with their degrees and frustration is included in the system. This assumption can enhance or delay the explosive transition to synchronization. Interestingly, a de-synchronization phenomenon occurs and the type of phase transition is also changed. Furthermore, we provide an analytical treatment based on a star graph, which resembles that obtained in scale-free networks. Finally, a self-consistent approach is implemented to study the de-synchronization regime. Our findings have important implications for controlling synchronization in complex networks because frustration is a controllable parameter in experiments and a discontinuous abrupt phase transition is always dangerous in engineering in the real world.

关键词： coupled phase oscillator explosive synchronization frustration

THE UPWIND FINITE ELEMENT SCHEME AND MAXIMUM PRINCIPLE FOR NONLINEAR CONVECTION-DIFFUSION PROBLEM

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Journal of Computational Mathematics 2004年第5期22卷 699-718页

作者： zhi-yongZhao jian-weiHu LPMCandISC SchoolofMathematicalSciencesNankaiUniverstyLiuHuiCenterforAppliedMathematicsNankaiUniversityTianjin300071China

In this paper, a kind of partial upwind finite element scheme is studied for twodimensional nonlinear convection-diffusion problem. Nonlinear convection term approximated by partial upwind finite element method considered over a mesh dual to the triangular grid, whereas the nonlinear diffusion term approximated by Galerkin method. A linearized partial upwind finite element scheme and a higher order accuracy scheme are constructed respectively. It is shown that the numerical solutions of these schemes preserve discrete maximum principle. The convergence and error estimate are also given for both schemes under some assumptions. The numerical results show that these partial upwind finite element scheme are feasible and accurate.

关键词： Convection-diffusion problem Partial upwind finite element Maximum principle

Rapid determination of radon monitor＇s calibration factors

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Nuclear Science and Techniques 2016年第5期27卷 188-192页

作者： zhi-Qiang Li De-Tao Xiao Gui-zhi Zhao Xi-Jun Wu jian Shan Qing-zhi Zhou zheng-Zhong He University of South China Hengyang 421001 China Hengyang Normal University Hengyang 421008 China

The monitors used to measure radon concentration must be calibrated,and the calibration factor of each measurement cycle should be ***,the determination time of calibration factors of NRL-Ⅱ radon monitors should be *** this study,a method is proposed to determine the calibration factors of radon monitors *** the proposed method,the calibration factor is initially determined in the 60-min measurement cycle;the calibration factor is then identified in the other measurement cycle on the basis of the principle that the calibration factor of the same radon monitor in different measurement cycles is inversely proportional to the number of a particles produced by ^(218)Po decay in this *** demonstrate that the calculated calibration factor of the different measurement cycles is consistent with the experimental calibration ***,this method is reliable and can be used to determine the calibration factor of radon monitors rapidly.

关键词：校准因子氡浓度监测仪快速测定测量周期监测器测定时间校正因子