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关键词： Galling mechanisms   Surface topography   Microstructure   Stainless steels  

摘要： This paper focuses on the galling mechanisms occurring in stainless steels and aims to provide a better comprehension of the effects of microstructure on galling resistance. Five stainless steels are studied in this paper, namely Nitronic60, AISI660, 316L, 316LN (austenitic stainless steels) and Uranus45 N (duplex austenite-ferrite). Both surface topography and in-depth microstructure are characterized in order to determine the consequences of galling apparition. Experimental investigations at macroscopic and microscopic scales show that galling can occur following several mechanisms. Galling leads to either adhesive wear spots randomly distributed on the surface (tolerant galling), adhesive wear initiated on the periphery of the pin (moderate galling) or abrasive wear and smearing (severe galling). Depending on these categories, the galling threshold and severity are highly variable. Studying these specific mechanisms can help us predict and eventually increase galling resistance for a given material couple. Thus, several microstructural investigations have been performed in order to discuss about the possible origins of these galling categories.

关键词： Unsupervised learning   Categorical clustering   Rough set theory   K-modes   Uncertainty  

摘要： Clustering is an unsupervised Machine Learning technique widely used to arrange a set of observations into distinct groups called clusters. The problem of categorical clustering has attracted much attention since many real world applications tend to produce such data types. The k-mode was among the first algorithms developed in this context. This algorithms uses the notion of modes to represent the centroids within the clusters. However, its major drawback lies in the random selection of the modes in each iteration during the clustering process. In this paper, we tackled this random selection issue and proposed a new method based on identifying the most adequate modes among a list of candidate ones. The proposed algorithm called Density Rough k-modes (DRk-M) is based on computing the density of each candidate mode to characterize the distribution of the observations around it. Then, we use the Rough Set Theory to deal with the uncertainty involved in this process. The DRk-M was experimented using real world datasets extracted from the UCI (University of California Irvine) Machine Learning Repository, the Global Terrorism Database (GTD) and a set of scrapped Tweets. The DRk-M was compared to many state of the art methods including the k-modes (1998), the Ng's method (2007), Cao's method (2012) and Bai's technique (2014) and it has shown great efficiency. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Quasi-coherent sheaf   Phantom map   Cover   Geometrical pure injective  

摘要： We give sufficient conditions to ensure that the ideal Phi(epsilon') of epsilon'-phantom maps in a locally lambda-presentable exact category (A, epsilon) is a (special) (pre)covering ideal, where epsilon' is an exact substructure of (A, epsilon). As a byproduct, we infer the existence of various covering ideals in categories of sheaves which have a meaningful geometrical motivation. In particular, we deal with a Zariski-local notion of phantom maps in categories of sheaves. We would like to point out that our approach is necessarily different from [18], as the categories involved in most of the examples we are interested in, do not have enough projective morphisms. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Extension fullness   Highest weight categories   Ind-completions   Modular representation theory  

摘要： We demonstrate equivalence between two definitions of lower finite highest weight categories. We also show that, in the presence of a duality, a lower finite highest weight structure on a category is unique. Finally, we give a proof for the known fact that any abelian category is extension full in its ind-completion. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Quantum groups   Triangulated categories   Fusion rings  

摘要： In this paper, we study derived versions of the fusion category associated to Lusztig's quantum group U-q. The categories that arise in this way are not semisimple but recovers the usual fusion ring when passing to Grothendieck rings. On the derived level it turns out that it is possible to define fusion for U-q without using the notion of tilting modules. Hence, we arrive at a definition of the fusion ring that makes sense in any spherical category. We apply this new definition to the small quantum group and we relate it with some rings appearing in [22]. (C) 2020 Elsevier Inc. All rights reserved.

摘要： Introduction: The role of functional imaging in Multiple Myeloma (MM) has evolved in recent years due to the increasing availability of high platform imaging and the prognostic information of imaging response after treatment, as observed in PET/CT studies. Diffusion weighted whole body MRI (DW-MRI) is a functional imaging technique with an emerging role in the management of MM patients (pts) due to its high sensitivity, but consistent data regarding its prognostic role in the detection of residual disease after treatment in MM are lacking. The Myeloma Response Assessment and Diagnosis System (MY-RADS) imaging recommendations have been recently published (Messiou C et al, Radiology 2019) in order to promote standardization in response assessment. Criteria for Response Assessment Category (RAC) have been proposed with a 5 point scale defining the probability of complete imaging response (i.e. RAC 1) or progressive disease after treatment (i.e. RAC 5), but this score still needs to be validated in clinical practice. For this purpose, we performed an external validation of RAC criteria according to MY-RADS in newly diagnosed MM pts in order to evaluate the prognostic role of this technique after autologous stem cell transplantation (ASCT). Furthermore, we tried to correlate the results of MY-RADS with those of minimal residual disease (MRD) assessment by flow cytometry (FCM). Patients and methods: We retrospectively analyzed the outcome of 60 MM pts (median age 63 years) diagnosed between January 2016 to January 2020 who underwent DW-MRI evaluation to assess the response at day +100 after ASCT, before maintenance. After anonymization, images were reviewed according to MY-RADS by Radiologists who were blinded to the results of clinical and biological data. Post ASCT Progression free survival (PFS) was calculated from the date of last ASCT (the second one in case of double ASCT) until progression or death from any cause. The predictive role of MRI RAC response on outcome

关键词： Frobenius categories   Triangulated categories   Topological categories   Equivalence coverings  

摘要： In [8], the continuous cluster category was introduced. This is a topological category whose space of isomorphism classes of indecomposable objects forms a Moebius band. It was found in [8] that, in order to have a continuously triangulated structure on this category, one needs at least two copies of each indecomposable object forming a 2-fold covering space of the Moebius band. This paper classifies all continuous triangulations of finite coverings of the basic continuous cluster category. This includes the connected 2-fold covering of Igusa-Todorov [8], the disconnected 2-fold covering of Orlov [13] and a third unexpected continuously add-triangulated 2-fold covering of the Moebius strip category. (C) 2020 Published by Elsevier B.V.

关键词： 污染减排   污染物浓度   生态环境   臭氧浓度   大气环境规划   协同控制   钢铁行业   规划院  

摘要： 生态环境部环境规划院大气环境规划研究所所长雷宇在2020(第三届)全国钢铁行业绿色发展大会上表示,PM2.5和臭氧协同控制是“十四五”规划的重要内容。从污染物浓度来看,我国PM2.5浓度是世界卫生组织准则值的3.6倍,臭氧是1.5倍;美丽中国建设需要PM2.5和臭氧浓度持续降低,污染减排不断深化。

关键词： 现代职业教育   职业教育理论   教育工作者   教育理论体系   社科基金课题   最终研究成果   深层次发展   理论体系构建  

摘要： 改革开放尤其是党的十八大提出"加快发展现代职业教育"以来,我国职业教育进入了快速发展期,职业教育工作者、研究者进行的职业教育理论研究也取得了丰硕成果。这些成果对当前职业教育发展实践进行了总结、反思和观照,同时也指导、规范和推动了现代职业教育实践向更高更深层次发展。其中,周明星教授等人所著的《中国现代职业教育理论体系——概念、范畴与逻辑》一书,作为国家社科基金课题的最终研究成果,更是针对当前职业教育理论进行了体系化、专门化的研究,被称为"一部探索中国现代职业教育理论体系的鼎新之作"。

关键词： 动补结构   认知结果范畴观   事件   语法范畴   语义范畴  

摘要： 当前结果范畴研究主要集中在动补(宾)结构的结果补语或结果宾语的句法语义关系上,一般将结果范畴看作一种语法范畴或语义范畴,两者理论内涵界定并不清楚。为突破理论认识瓶颈,基于认知语言学原型范畴理论和事件整体分析视角,重新界定结果范畴语义内涵,将结果范畴从事件构成要素视角看作是“达成”与“完成”事件的共有语义构成要素,两者区别在其事件时间属性特征(时点性、时段性)的差异上,据此可以从其作为语义构成要素和句法实现两个层面进行有效分析,为从事件语义学视角分析结果范畴奠定理论基础。