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Capturing metal clusters at the strong-interaction region to reverse Ostwald ripening

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Science China materials 2024年第4期67卷 1363-1364页

作者： Shuheng Tian Ding ma beijing National Laboratory for Molecular Sciences New Cornerstone Science LaboratoryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

High-temperature interactions induce sintering of metal nanoparticles(NPs) on heterogeneous catalyst surfaces, leading to reduced surface area and active site loss through Ostwald ripening [1]. This irreversible deactivation necessitates costly catalyst replacement, notably impacting metals like copper in hydrogenation and reforming reactions [2].

关键词： catalyst reforming irreversible

Unconfined compressive strength and failure behaviour of completely weathered granite from a fault zone

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Journal of Mountain Science 2024年第6期21卷 2140-2158页

作者： DU Shaohua ma Jinyin ma Liyao ZHAO Yaqian School of Civil Engineering and Architecture Henan University of Science and TechnologyLuoyang 471023China School of Resources and Safety Engineering Central South UniversityChangsha 410083China China Railway 18th Bureau Group Co. LtdTianjin 300222 China China General Nuclear Power Corporation Shenzhen 518031China

Understanding the strength characteristics and deformation behaviour of the tunnel surrounding rock in a fault zone is significant for tunnel stability *** this study,a series of unconfined compression tests were conducted to investigate the mechanical characteristics and failure behaviour of completely weathered granite(CWG)from a fault zone,considering with height-diameter(h/d)ratio,dry densities(ρd)and moisture contents(ω).Based on the experimental results,a regression mathematical model of unconfined compressive strength(UCS)for CWG was developed using the Multiple Nonlinear Regression method(MNLR).The research results indicated that the UCS of the specimen with a h/d ratio of 0.6 decreased with the increase ofω.When the h/d ratio increased to 1.0,the UCS increasedωwith up to 10.5%and then ***ρd is conducive to the improvement of the UCS at anyω.The deformation and rupture process as well as final failure modes of the specimen are controlled by h/d ratio,ρd andω,and the h/d ratio is the dominant factor affecting the final failure mode,followed byωandρ*** specimens with different h/d ratio exhibited completely different fracture mode,i.e.,typical splitting failure(h/d=0.6)and shear failure(h/d=1.0).By comparing the experimental results,this regression model for predicting UCS is accurate and reliable,and the h/d ratio is the dominant factor affecting the UCS of CWG,followed byρd and thenω.These findings provide important references for maintenance of the tunnel crossing other fault fractured zones,especially at low confining pressure or unconfined condition.

关键词： Fault fracture zone Completely weathered granite(CWG) Unconfined compression strength(UCS) Multiple nonlinear regression model

Mitigate noisy data for smart IoT via GAN based machine unlearning

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Science China(Information Sciences) 2024年第3期67卷 62-78页

作者： Zhuo ma Yilong YANG Yang LIU Xinjing LIU Jianfeng ma School of Cyber Engineering Xidian University State Key Laboratory of Integrated Services Networks (ISN)

With the development of IoT applications, machine learning dramatically improves the utility of variable IoT systems such as autonomous driving. Although the pretrain-finetune framework can cope well with data heterogeneity in complex IoT scenarios, the data collected by sensors often contain unexpected noisy data, e.g., out-of-distribution(OOD) data, which leads to the reduced performance of fine-tuned models. To resolve the problem, this paper proposes Mu GAN, a method that can mitigate the side-effect of OOD data via the generative adversarial network(GAN)-based machine unlearning. Mu GAN follows a straightforward but effective idea to mitigate the performance loss caused by OOD data, i.e., “flashbacking” the model to the condition where OOD data are excluded from model training. To achieve the goal, we design an adversarial game, where a discriminator is trained to identify whether a sample belongs to the training set by observing the confidence score. Meanwhile, a generator(i.e., the target model) is updated to fool the discriminator into believing that the OOD data are not included in the training set but others do. The experimental results show that benefiting from the high unlearning rate(more than 90%) and retention rate(99%), Mu GAN succeeds in lowering the model performance degradation caused by OOD data from 5.88% to 0.8%.

关键词： machine unlearning generative adversarial network out of distribution data Internet of Thing neural network

3D simulation of image-defined complex internal features using the numerical manifold method

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Science China(Technological Sciences) 2024年第4期67卷 1023-1039页

作者： WU Jie ma GuoWei School of Civil and Transportation Engineering Hebei University of TechnologyTianjin 300401China Tianjin Key Laboratory for Prefabricated Building and Intelligent Construction Tianjin 300401China

The numerical simulation of internal features,such as inclusions and voids,is important to analyze their impact on the performance of composite ***,the complex geometries of internal features and the induced continuous-discontinuous(C-D)deformation fields are challenges to their numerical *** this study,a 3D approach using a simple mesh to simulate irregular internal geometries is developed for the first *** the help of a developed voxel crack model,image models that are efficient when recording complex geometries are directly imported into the *** reconstructions,which are usually labor-intensive,are excluded from this ***,using image models as the geometric input,image processing techniques are applied to detect material interfaces and develop contact ***,the C-D deformations of the complex internal features are directly calculated based on the numerical manifold *** accuracy and convergence of the developed3D approach are examined based on multiple *** 3D C-D simulation of sandstones with naturally formed complex microfeatures demonstrates the capability of the developed approach.

关键词： 3D continuous-discontinuous simulation image-based simulation complex internal features numerical manifold method voxel crack model structured mesh

Enhancing capacitive deionization performance and cyclic stability of nitrogen-doped activated carbon by the electro-oxidation of anode materials

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Chinese Journal of Chemical Engineering 2024年第5期69卷 23-33页

作者： Xiaona Liu Baohua Zhao Yanyun Hu Luyue Huang Jingxiang ma Shuqiao Xu Zhonglin Xia Xiaoying ma Shuangchen ma School of Environmental Science and Engineering North China Electric Power UniversityBaoding 071003China Huadian Zhengzhou machinery Design and Research Institute Co. LtdZhengzhou 450002China Huadian Inner Mongolia Energy Co. Ltd.Baotou Power Generation BranchBaotou 014013China

Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.

关键词： Anodic oxidation Capacitive deionization Cyclic stability N-doping

Advancements in machine learning for material design and process optimization in the field of additive manufacturing

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China Foundry 2024年第2期21卷 101-115页

作者： Hao-ran Zhou Hao Yang Huai-qian Li Ying-chun ma Sen Yu Jian shi Jing-chang Cheng Peng Gao Bo Yu Zhi-quan Miao Yan-peng Wei National Key Laboratory of Advanced Casting Technologies Shenyang Research Institute of Foundry Co.Ltd.CAMShenyang 110022China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Key Laboratory of Space Physics Beijing 100076China School of materials Science and Engineering Nanyang Technological University639798Singapore

Additive manufacturing technology is highly regarded due to its advantages,such as high precision and the ability to address complex geometric ***,the development of additive manufacturing process is constrained by issues like unclear fundamental principles,complex experimental cycles,and high *** learning,as a novel artificial intelligence technology,has the potential to deeply engage in the development of additive manufacturing process,assisting engineers in learning and developing new *** paper provides a comprehensive overview of the research and applications of machine learning in the field of additive manufacturing,particularly in model design and process ***,it introduces the background and significance of machine learning-assisted design in additive manufacturing *** then further delves into the application of machine learning in additive manufacturing,focusing on model design and process ***,it concludes by summarizing and forecasting the development trends of machine learning technology in the field of additive manufacturing.

关键词： additive manufacturing machine learning material design process optimization intersection of disciplines embedded machine learning

基于租房数据的京津冀城市群跨城通勤特征及影响因素研究

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地理科学进展 2024年第5期43卷 841-853页

作者：张纯马畅北京交通大学建筑与艺术学院北京100044 北京交通大学国土空间与交通协同发展研究院北京100044 北京交通大学交通运输学院北京100044

近年来中国城市群都市圈尺度的跨城通勤现象愈加频繁。相对于国际大城市的通勤圈,国内跨城通勤特征与影响因素仍不明晰。论文以京津冀城市群为例,基于贝壳App租房者的双城通勤位置数据,采用基于GIS的OD(origin-destination)分析与空间... 详细信息

近年来中国城市群都市圈尺度的跨城通勤现象愈加频繁。相对于国际大城市的通勤圈,国内跨城通勤特征与影响因素仍不明晰。论文以京津冀城市群为例,基于贝壳App租房者的双城通勤位置数据,采用基于GIS的OD(origin-destination)分析与空间统计分析,考察跨城通勤现象的空间分布特征;并辅以个体通勤时间为因变量的普通最小二乘法(ordinary least squares,OLS)、地理加权回归(geographically weighted regression,GWR)模型,揭示空间变量和个人社会属性综合作用下的影响机制。结果表明:①京津冀城市群的跨城通勤呈现出明显的廊道分布特征,集中在东部、东南与西南三条通勤廊道上;②跨城通勤距离已经超越都市圈传统研究聚焦的30~50 km范围;③跨城通勤群体占租房总量20%以上的地区,位于廊坊燕郊开发区、固安县、保定涿州市等地,形成高频通勤的“环京通勤带”;④跨城通勤个体层面的GWR回归显示了职住两地工资差异、租房价格及居住地到高铁站距离等因素对通勤时间具有空间异质性影响。长时间跨城通勤动机存在差异,部分天津跨城通勤者主要为提高居住质量和工资,而部分廊坊、保定通勤者则为了提高工资和节省房租。研究结果可为新型城镇化战略下的城市群都市圈城镇空间合理布局与综合交通协同优化提供借鉴。

关键词：城市群跨城通勤空间分布职住空间关系 GWR 京津冀

Progress in the preparation,identification and biological activity of walnut peptides

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未来食品学报(英文) 2024年第3期4卷 205-220页

作者： chang Liu Zijie Zhang Yuting Shang Siting Li Junxi Xia Yiling Tian Yingmin Jia Aijin ma School of Food and Health Beijing Technology and Business UniversityBeijing 100048China Hebei Yangyuan ZhiHui Beverage Co. Ltd.Hengshui 053000China Institution of Chinese Walnut Industry Hengshui 053000China Hebei Key Laboratory of Walnut Nutritional Function and Processing Technology Hengshui 053000China College of Food Science and Technology Hebei Agricultural UniversityBaoding 071000China

Walnuts are rich in protein and are a high-quality plant protein *** recent years,with the growth of consumer demand for functional food and food for special medical purpose,the use of walnut protein for the preparation of functional walnut peptide ingredients or additives and other compositions has received increasing ***,the improvement of the yield of walnut peptides and the clarification of their functional activities are the bottlenecks that limit the development of these *** this end,this article reviews the pretreatment,preparation,purification and identification processes of walnut peptides,as well as their biological activities such as antioxidant activity,antitumour activity,improvement of memory,antihypertension and regulation of metabolic disorders are elaborated to provide a reference for the industrial development of walnut peptides.

关键词： Walnut Peptide Extraction Isolation Purification Identification Biological activity

A combined Liouville integrable hierarchy associated with a fourth-order matrix spectral problem

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Communications in Theoretical Physics 2024年第7期76卷 1-8页

作者： Wen-Xiu ma Department of mathematics Zhejiang Normal UniversityJinhua 321004China Department of mathematics King Abdulaziz UniversityJeddah 21589Saudi Arabia Department of mathematics and Statistics University of South Florida TampaFL 33620-5700United States of America material Science Innovation and Modelling Department of Mathematical SciencesNorth-West UniversityMafikeng CampusMmabatho 2735South Africa

This paper aims to propose a fourth-order matrix spectral problem involving four potentials and generate an associated Liouville integrable hierarchy via the zero curvature formulation.A bi-Hamiltonian formulation is furnished by applying the trace identity and a recursion operator is explicitly worked out,which exhibits the Liouville integrability of each model in the resulting *** specific examples,consisting of novel generalized combined nonlinear Schrodinger equations and modified Korteweg-de Vries equations,are given.

关键词： integrable hierarchy Hamiltonian structure zero curvature equation Lax pair matrix spectral problem