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Effects of the microstructure of twin roll cast and hot rolled plates on the surface quality of presensitized plates

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International Journal of minerals,Metallurgy and Materials 2014年第9期21卷 919-924页

作者： yuan-Zhi Zhu Ya-Feng Zhang Chao-qi Zhao Feng Zhou College of Mechanical and Electrical Engineering North China University of Technology Key Laboratory for Ferrous Metallurgy and Resources Utilization of the ministry of Education Wuhan University of Science and Technology

The effect of the microstructure of plates fabricated both in the traditional process, involving casting, hot rolling and cold rolling （HR）, and in the novel twin roll casting ＋ cold rolling （TRC） process on the surface quality of presensitized （PS） plates was analyzed by optical microscopy （OM）, scanning electron microscopy （SEM）, and energy-dispersive X-ray spectroscopy （EDXS）. The formation of pores on the surface of the electrolyzed HR plate could be attributed to the presence of approximately 1-μm-sized large Al-Fe precipitates in the HR plate compared to the smaller precipitates in the TRC plate. Moreover, residual graphite lubricants used during the TRC process were entrapped on the surface of the TRC plate during the subsequent rolling process. The entrapped pollutants tended to further deteriorate the formation of pores on the surface of the TRC plate, and no residual carbon was detected on the surface of the HR plate. Furthermore, the surface quality of the TRC plate can be improved by surface cleaning before the cold rolling process, which could dramatically lower the residual graphite on the surface.

关键词： aluminum plates microstructure presensitizing surface quality

Automated Testing of Web Applications Using Combinatorial Strategies

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Journal of Computer Science & Technology 2017年第1期32卷 199-210页

作者： Xiao-Fang qi Zi-yuan Wang Jun-qiang Mao Peng Wang School of Computer Science and Engineering Southeast University Nanjing 211189 China Key Laboratory of Computer Network and Information Integration Ministry of Education Nanjing 211189 China School of Computer Science and Technology Nanjing University of Posts and Telecommunications Nanjing 210023 China

Recently, testing techniques based on dynamic exploration, which try to automatically exercise every possible user interface element, have been extensively used to facilitate fully testing web applications. Most of such testing tools are however not effective in reaching dynamic pages induced by form interactions due to their emphasis on handling client-side scripting. In this paper, we present a combinatorial strategy to achieve a full form test and build an automated test model. We propose an algorithm called pairwise testing with constraints （PTC） to iraplement the strategy. Our PTC algorithm uses pairwise coverage and handles the issues of semantic constraints and illegal values. We have implemented a prototype tool ComjaxTest and conducted an empirical study on five web applications. Experimental results indicate that our PTC algorithm generates less form test cases while achieving a higher coverage of dynamic pages than the general pairwise testing algorithm. Additionally, our ComjaxTest generates a relatively complete test model and then detects more faults in a reasonable amount of time, as compared with other existing tools based on dynamic exploration.

关键词： automated testing combinatorial testing web application

Interfacial reaction mechanism of TiBw/Ti6Al4V composites and Inconel 718 alloys by GTAW heat transmission

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Science China(Technological Sciences) 2019年第12期62卷 2293-2301页

作者： GAO YaNan HUANG LuJun SUN yuan AN qi ZHANG Jie GENG Lin State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Institute of Metal Research Chinese Academy of SciencesSheryang 110016China

A good joint of Ti Bw/Ti6Al4V composites and Inconel 718 alloys was obtained by Gas Tungsten Arc Welding(GTAW) heat transmission. The interfacial reaction mechanism of joint was investigated and analyzed in details. Owing to the heat input applied on the surface of Ti Bw/Ti6Al4V composites, a solid-state reaction layer appeared at the interface of Ti Bw/Ti6Al4 V composites to Inconel 718 alloys. The thickness of the reaction layer was obviously increased with increasing heat *** of reaction layer mainly depended on the diffusion of elements of Ti and Ni through the interface during welding to form solid solutions and intermetallic compounds(IMCs). The reaction layer can be divided into Ti-rich zone(layer 2) and Nirich zone(layer 1). In Ni-rich zone, relatively coarse dendrites were the predominant, however, more brittle IMCs like Ti2Ni were found in the Ti-rich zone. micro hardness of reaction layer was much higher than that of base metal. While a slight decrease of hardness was found between Ti-rich zone and Ni-rich zone due to the formation of TiNi.

关键词： TiBw/Ti6Al4V composites Inconel 718 alloys interfacial reaction heat transmission microstructures

Preparation of Polylactide/Poly(ether)urethane Blends with Excellent Electro-actuated Shape Memory via Incorporating Carbon Black and Carbon Nanotubes Hybrids Fillers

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Chinese Journal of Polymer Science 2018年第10期36卷 1175-1186页

作者： yuan Wei Rui Huang Peng Dong Xiao-Dong qi qiang Fu College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering Sichuan University

In this work, hybrid conductive fillers of carbon black （CB） and carbon nanotubes （CNTs） were introduced into polylactide （PLA）/thermoplastic poly（ether）urethane （TPU） blend （70/30 by weight） to tune the phase morphology and realize rapid electrically actuated shape memory effect （SME）. Particularly, the dispersion of conductive fillers, the phase morphology, the electrical conductivities and the shape memory properties of the composites containing CB or CB/CNTs were comparatively investigated. The results suggested that both CB and CNTs were selectively localized in TPU phase, and induced the morphological change from the sea-island structure to the co-continuous structure. The presence of CNTs resulted in a denser CB/CNTs network, which enhanced the continuity of TPU phase. Because the formed continuous TPU phase provided stronger recovery driving force, the PLA/TPU/CB/CNTs composites showed better shape recovery properties compared with the PLA/TPU/CB composites at the same CB content. Moreover, the CB and CNTs exerted a synergistic effect on enhancing the electrical conduetivities of the composites. As a result, the prepared composites exhibited excellent electrically actuated SME and the shape recovery speed was also greatly enhanced. This work demonstrated a promising strategy to achieve rapid electrically actuated SME via the addition of hybrid nanoparticles with self-networking ability in binary PLA/TPU blends over a much larger composition range.

关键词： Polymer composites Shape memory polymer Co-continuous structure Self-networking behavior Hybrid filler

Characterization of the Convoluted 3D Internetallic Phases in a Recycled Al Alloy by Synchrotron X-ray Tomography and Machine Learning

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Acta Metallurgica Sinica(English Letters) 2022年第1期35卷 115-123页

作者： Zhenhao Li Ling qin Baisong Guo Junping yuan Zhiguo Zhang Wei Li Jiawei mi Institute of Advanced Wear Resistant and Functional Materials Jinan UniversityGuangzhou510632China Jewelry Institute Guangzhou Panyu PolytechnicGuangzhou511487China Department of Engineering University of HullEast YorkshireHullHU67RXUK

Fe-rich intermetallic phases in recycled Al alloys often exhibit complex and 3D convoluted structures and *** are the common detrimental intermetallic phases to the mechanical properties of recycled Al *** this study,we used synchrotron X-ray tomography to study the true 3D morphologies of the Ferich phases,Al_(2)Cu phases and casting defects in an ascast Al-5Cu-1.5Fe-1Si *** learning-based image processing approach was used to recognize and segment the diff erent phases in the 3D tomography image *** the studied condition,theβ-Al_(9)Fe_(2)Si_(2)andω-Al_(7)Cu_(2)Fe are found to be the main Fe-rich intermetallic ***β-Al_(9)Fe_(2)Si_(2)phases exhibit a spatially connected 3D network structure and morphology which in turn control the 3D spatial distribution of the Al_(2)Cu phases and the shrinkage *** Al_(3)Fe phases formed at the early stage of solidification aff ect to a large extent the structure and morphology of the subsequently formed Fe-rich intermetallic *** machine learning method has been demonstrated as a powerful tool for processing big datasets in multidimensional imaging-based materials characterization work.

关键词： Recycled Alalloy Solidifi cation Synchrotron X-ray tomography Machine learning Fe-rich intermetallic phases

Risk-preparedness mechanism and audit quality:Evidence from mandatory increase of professional indemnity insurance and professional risk fund

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China Journal of Accounting Research 2023年第1期16卷 103-125页

作者： Yue qi qingbo yuan School of Business Sun Yat-sen UniversityGuangzhouChina Department of Accounting The University of MelbourneAustralia

We examine the risk-preparing benefits of Chinese audit firms’professional indemnity insurance(PII)and professional risk fund(PRF)by using the Notice on Adjusting the Application Requirement of Audit Firms for Securities Qualifications as an exogenous *** policy requires audit firms to raise the sum of the cumulative compensation limit of their PII and PRF from 6 million to 80million *** is found,first,that the capital market regards this policy revision as a signal to strengthen investor protection and responds positively;client firms with high audit risks have a stronger ***,auditors’governance of financial information has strengthened,resulting in the significant improvement of their clients’financial reporting quality,with a stronger effect on firms with higher earnings management *** is no evidence that audit firms pass the costs on to their ***,the mismatch between auditors and new client firms is *** show that in an emerging market with weak investor protection,establishing a sound risk-preparedness mechanism for audit firms and strengthening the capacity for civil compensation ex post greatly improve the adaptive degree between international auditing standards and the legal environment of China,thereby enhancing the overall service quality of the audit market.

关键词： Professional indemnity insurance Professional risk fund Audit quality Audit fees Auditor allocation

Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

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International Journal of minerals,Metallurgy and Materials 2016年第8期23卷 881-890页

作者： Ying-yi Zhang Wei Lü yuan-hong qi Zong-shu Zou College of Materials Science and Engineering Chongqing University State Key Laboratory of Advance Steel Processes and Products Central Iron and Steel Research Institute School of Material and Metallurgy Northeastern University

A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w（CaO）/w（SiO_2） ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al_2O_3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100：16.17：59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca_2 SiO_4 and Ca_（12）Al_（14）O_（33）, with small amounts of Fe Al_2O_4, CaAl_2O_4, and Ca_2Al_2SiO_7.

关键词： bauxite reduction smelting recovery rate calcium aluminate slag

SegNet-based first-break picking via seismic waveform classification directly from shot gathers with sparsely distributed traces

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Petroleum Science 2022年第1期19卷 162-179页

作者： San-Yi yuan Yue Zhao Tao Xie Jie qi Shang-Xu Wang State Key Laboratory of Petroleum Resources and Prospecting CNPC Key Laboratory of Geophysical ExplorationChina University of PetroleumBeijing 102249China China Oilfield Services Ltd. TangguTianjin 300452China University of Oklahoma ConocoPhillips School of Geology and GeophysicsNormanOKUSA

Manually picking regularly and densely distributed first breaks(FBs)are critical for shallow velocitymodel building in seismic data ***,it is time *** employ the fullyconvolutional Seg Net to address this issue and present a fast automatic seismic waveform classification method to pick densely-sampled FBs directly from common-shot gathers with sparsely distributed *** feeding a large number of representative shot gathers with missing traces and the corresponding binary labels segmented by manually interpreted fully-sampled FBs,we can obtain a welltrained Seg Net *** any unseen gather including the one with irregular trace spacing is inputted,the Seg Net can output the probability distribution of different categories for waveform *** FBs can be picked by locating the boundaries between one class on post-FBs data and the other on pre-FBs *** land datasets with each over 2000 shots are adopted to illustrate that one well-trained 25-layer Seg Net can favorably classify waveform and further pick fully-sampled FBs verified by the manually-derived ones,even when the proportion of randomly missing traces reaches50%,21 traces are missing consecutively,or traces are missing regularly.

关键词： First-break picking Deep learning Irregular seismic data Waveform classification

Review on the petroleum market in China:history,challenges and prospects

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Petroleum Science 2020年第6期17卷 1779-1794页

作者： Si-yuan Chen qi Zhang Benjamin Mclellan Tian-Tian Zhang School of Economics and Management China University of Petroleum-BeijingBeijing 102249China Academy of Chinese Energy Strategy China University of Petroleum-BeijingBeijing 102249China Graduate School of Energy Science Kyoto UniversityKyotoJapan

The petroleum industry plays an essential role in driving China's economic *** the past few decades,severa reforms in the petroleum industry have been implemented;however,there are still some is sues that have not been resolved Moreover,with the new-normal economy,the transition to green energy and international trade disputes,the petroleum marke is also facing emerging ***,the purpose of the present study is to review the historical development o China's petroleum market,identify the current challenges and propose corresponding countermeasures for future prospects As a conclusion,five main challenges are highlighted totally,namely lack of marketization,excess oil refining capacity,hig external dependency,environment pollution and unstable international trading *** address these challenges it is encouraged to deepen petroleum market reform,accelerate the elimination of inefficient refining capacity,diversify of supply sources,as well as improve domestic petroleum enterprises'ability to resist price risks.

关键词： China's petroleum market Petroleum products Market reform