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Biosafety and Health 2023年第1期5卷 8-13页

作者： Tao Yun China science and technology Exchange center Beijing 100045China

Since the coronavirus disease 2019(COVID-19)pandemic,major innovative-oriented countries have adopted various science and technology innovation(STI)policies to address global public health challenges.Using data from the Organization for Economic Co-operation and Development STI Database,this study analyzed international STI policies in response to the COVID-19 pandemic.The findings revealed that the pandemic has dramatically stimulated the application of STI policies,and there are commonalities and differences in the STI policies of different countries.Meanwhile,COVID-19 has disrupted planning for allocating resources for STIs,leading to duplication and inefficiency.Based on the findings,this study recommends increasing research investment to address the long-term challenges of major infectious diseases,strengthening support for enterprises,promoting data sharing and openness,enhancing the internationalization of scientific research,strengthening scientific consultation and communication,and devoting more policy attention to vulnerable groups.

关键词： COVID-19 Organizational innovation Policy making Health policy

超轻超弹陶瓷纳米纤维气凝胶:重新认识古老的陶瓷材料

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science Bulletin 2023年第8期68卷 753-755页

作者：刘一涛丁彬 innovation center for Textile science and technology Donghua UniversityShanghai 200051China

Ceramics,a huge family of inorganic compounds including oxides,nitrides,carbides,silicates,aluminates,phosphates,etc.,are among the most ancient materials whose service to mankind could date back to~7000 years ago.Owing to strong covalent or ionic bonds linking the constituent atoms,ceramics possess good mechanical strength and heat resistance,and have long been used as the structural components particularly at high temperatures.

关键词：陶瓷材料 ceramics 气凝胶

Exploring nonlinear spatiotemporal effects for personalized next point-of-interest recommendation

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信息与电子工程前沿:英文版 2023年第9期24卷 1273-1286页

作者： Xi SUN Zhimin LV Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

Next point-of-interest(POI)recommendation is an important personalized task in location-based social networks(LBSNs)and aims to recommend the next POI for users in a specific situation with historical check-in data.State-of-the-art studies linearly discretize the user’s spatiotemporal information and then use recurrent neural network(RNN)based models for modeling.However,these studies ignore the nonlinear effects of spatiotemporal information on user preferences and spatiotemporal correlations between user trajectories and candidate POIs.To address these limitations,a spatiotemporal trajectory(STT)model is proposed in this paper.We use the long short-term memory(LSTM)model with an attention mechanism as the basic framework and introduce the user’s spatiotemporal information into the model in encoding.In the process of encoding information,an exponential decay factor is applied to reflect the nonlinear drift of user interest over time and distance.In addition,we design a spatiotemporal matching module in the process of recalling the target to select the most relevant POI by measuring the relevance between the user’s current trajectory and the candidate set.We evaluate the performance of our STT model with four real-world datasets.Experimental results show that our model outperforms existing state-of-the-art methods.

关键词： Point-of-interest recommendation Spatiotemporal effects Long short-term memory(LSTM) Attention mechanism

Monitoring and diagnosis of complex production process based on free energy of Gaussian–Bernoulli restricted Boltzmann machine

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Journal of Iron and Steel Research(International) 2023年第5期30卷 971-984页

作者： Qian-qian Dong Qing-ting Qian Min Li Gang Xu Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

Online monitoring and diagnosis of production processes face great challenges due to the nonlinearity and multivariate of complex industrial processes.Traditional process monitoring methods employ kernel function or multilayer neural networks to solve the nonlinear mapping problem of data.However,the above methods increase the model complexity and are not interpretable,leading to difficulties in subsequent fault recognition/diagnosis/location.A process monitoring and diagnosis method based on the free energy of Gaussian-Bernoulli restricted Boltzmann machine(GBRBM-FE)was proposed.Firstly,a GBRBM network was established to make the probability distribution of the reconstructed data as close as possible to the probability distribution of the raw data.On this basis,the weights and biases in GBRBM network were used to construct F statistics,which represents the free energy of the sample.The smaller the energy of the sample is,the more normal the sample is.Therefore,F statistics can be used to monitor the production process.To diagnose fault variables,the F statistic for each sample was decomposed to obtain the Fv statistic for each variable.By analyzing the deviation degree between the corresponding variables of abnormal samples and normal samples,the cause of process abnormalities can be accurately located.The application of converter steelmaking process demonstrates that the proposed method outperforms the traditional methods,in terms of fault monitoring and diagnosis performance.

关键词： Process monitoring Fault diagnosis Gaussian–Bernoulli restricted Boltzmann machine Energy function Free energy Converter steelmaking production process

Cu2O-templated fabrication of Ni(OH)2·0.75H2O hollow tubes for electrocatalytic oxygen evolution reaction

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Progress in Natural science:Materials International 2022年第5期32卷 554-560页

作者： Yu Zhang Xueai Teng Zequn Ma Rongming Wang Woon-Ming Lau Aixian Shan Beijing Advanced innovation center for Materials Genome Engineering & center for Green innovation School of Mathematics and Physics University of Science and Technology Beijing Beijing Advanced innovation center for Materials Genome Engineering Beijing Key Laboratory for Magneto-Photoelectrical Composite and Interface Science School of Mathematics and Physics University of Science and Technology Beijing Institute of Materials science and Devices School of Materials Science and Engineering Suzhou University of Science and Technology Shunde innovation School of University of science and technology Beijing

Cu2O is an ideal template material for the preparation of transition metal hydroxide/oxyhydroxides with oxygen evolution reaction(OER) enhanced catalytic performance. Here, inspired by Pearson’s principle, Cu2O wires were prepared and used as a sacrificial template to prepare Ni(OH)2·0.75H2O hollow tubes(Ni(OH)2HTs) with highly improved surface roughness. Benefiting from unique structural advantages, the Ni(OH)2HTs showed excellent catalytic activity, rapid kinetics and a long-term stability as the OER catalyst, where an overpotential of only 207mV was required to drive a current density of 10 mA cm-2, an ideal kinetics with a Tafel slope as 79.8 mV dec-1was calculated, and no obvious attenuation in chronoamperometry was discovered after operation for 24 h. This paper provides a novel template-assisted strategy to prepare high-performance transition metal-based OER catalysts possessing hollow and tubular structures.

关键词： Ni(OH) 2 hollow tube Cu 2 O wire Template One-dimensional hollow structure Oxygen evolution reaction

Characteristics of SEN clogging and adhesive behavior of oxide inclusion during continuous casting of Ti-stabilized ultra-pure ferritic stainless steels

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Journal of Iron and Steel Research(International) 2023年第10期30卷 1939-1951页

作者： Xue-feng Bai Yan-hui Sun Hui-bin Wu Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing100083China

Submerged entry nozzle(SEN)clogging during continuous casting of Ti-stabilized ultra-pure ferritic stainless(Ti-UPFS)steels was systematically investigated via cross-sectional analysis and acid dissolution treatment.The SEN deposit profile was characterized as occurring in three major layers:(1)an eroded refractory layer;(2)an initial adhesive layer comprised an Al_(2)O_(3)-ZrO_(2) composite sub-layer and a dense Al_(2)O_(3)-based deposit sub-layer;and(3)a porous multiphase deposit layer mainly consisting of MgO·Al_(2)O_(3),CaO-Al_(2)O_(3),and CaO-TiOx.The MgO·Al_(2)O_(3)-rich inclusions did not adhere directly to the eroded refractory but were entrapped during the deposit growth.Results of inclusion characterization in the tundish revealed that the MgO·Al2O3-rich particles present in the tundish served as the primary source of clogging deposits.Furthermore,a novel cavity-induced adhesion model by circular approximation was established to explain the effects of complex inclusion characteristics and refractory material type on adhesion force.A high number of small MgO·Al_(2)O_(3) inclusions were expected to accelerate the buildup of clogging deposits.Improving the modification of MgO·Al_(2)O_(3)-rich inclusions in the size range of 2-4μm by Ca treatment was crucial to minimizing the risk of SEN clogging during the continuous casting of Ti-UPFS steels.

关键词： Ti-stabilized ultra-pure ferritic stainless steel Submerged entry nozzle clogging MgO·Al_(2)O_(3)-rich inclusion Adhesion Continuous casting

Solidification structure simulation and casting process optimization of GCr15 bloom alloy

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China Foundry 2022年第1期19卷 63-74页

作者： Jie Li Hao-tian Wu Yang Liu Yan-hui Sun Collaborative innovation center of Steel technology University of Science and Technology BeijingBeijing 100083China

Based on the solidification heat transfer model and CAFÉmodel,the solidification structure of GCr15 bloom alloy was studied.Using nail shooting and acid etching experiments,the solidification models were verified.The secondary dendrite arm spacing(SDAS)model of GCr15 was obtained by simulation calculation and metallographic observation.With the increase of casting speed,the SDAS,equiaxed crystal ratio(ECR)and average grain size increase.With the rise of superheat,the SDAS increases in the 20-70 mm of thickness and decreases in the 80-160 mm of thickness.The ECR decreases and the average grain size increases with the increase of superheat.With the increase of specific water flow,both the SDAS and ECR decrease.The minimum average grain size is obtained when the specific water flow is 0.20 L·kg^(-1).The central carbon segregation index is reduced from 1.11 to 1.075.

关键词： numerical simulation continuous casting equiaxed crystal ratio secondary dendrite arm spacing carbon segregation

Effect of Sn doping concentration on the oxidation of Al-containing MAX phase(Ti_(3)AlC_(2))combining simulation with experiment

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Fundamental Research 2022年第1期2卷 114-122页

作者： Chunyu Guo Enhui Wang Yunsong Liu Yapeng Zheng Tao Yang Xinmei Hou Beijing Advanced innovation center for Materials Genome Engineering Collaborative Innovation Center of Steel TechnologyUniversity of Science and Technology BeijingBeijing 100083China

Sn doping is usually adopted to prepare Ti_(3)AlC_(2)in mass production because it can reduce the synthesis temperature while increasing the phase purity.However,excessive Sn doping usually deteriorates the oxidation resistance of Ti_(3)AlC_(2).Therefore,an appropriate Sn doping concentration is a vital issue.In this work,the effect of Sn doping concentration on the oxidation behavior of Ti_(3)AlC_(2)was systematically investigated by combining theoretical calculations and experimental methods.Density function theory calculations suggest that the oxygen adsorption mechanisms for the(001)surface of Ti_(3)AlC_(2)with and without Sn doping are similar,and Ti-O bonds are always preferentially formed.The molecular dynamics simulation further indicates that Al atoms have a faster diffusion rate during the oxidation process.Therefore,a continuous Al_(2)O_(3)layer can form rapidly at high temperature.Nevertheless,when the Sn doping concentration exceeds 10 mol%,the continuity of the Al_(2)O_(3)layer is destroyed,thereby impairing the oxidation resistance of Ti_(3)AlC_(2).Furthermore,oxidation experiments verify the above results.The oxidation mechanisms of Ti3AlC2 with different Sn doping concentrations are also proposed.

关键词： MAX phase Sn doping Density function theory Molecular dynamics Oxidation resistance

Formation and thermodynamics of CaS-bearing inclusions during Ca treatment in oil casting steels

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 573-587页

作者： Xue-feng Bai Yan-hui Sun Rui-mei Chen Yi-min Zhang Yi-fan Cai Collaborative innovation center of Steel technology University of Science and Technology Beijing

Industrial experiments were carried out to investigate the formation of CaS-bearing inclusion during Ca double modification in oil casting steels using polished cross sections and electrolytic extraction. Immediately after Ca addition, the role of newly generated CaS as an intermediate reaction product, which modified the Al_2O_3 inclusion into a liquid calcium aluminate, was confirmed. The formation of transient CaS was attributed to the high surface segregation of S at the liquid steel-calcium vapor interface, where a simple site coverage model based upon the Langmuir adsorption equation was established. Moreover, a CaS outer layer surrounding the liquid calcium aluminate was attained mainly in the tundish, which was distributed unevenly on the surface of liquid particles according to the three-dimensional mapping results. The surface of a well-modified calcium aluminate with higher CaO activity and Al_2O_3 activity under bulk composition conditions in the tundish acted as a favorable site for the generation of CaS. Additionally, CaS could be precipitated directly onto existing inclusions during solidification of the steel, which led to various morphologies of CaS-bearing inclusions in slabs. Furthermore, the phase transformation of inclusions during solidification was strongly influenced both by the S content and the Ca/S ratio in the tundish via thermodynamics.

关键词： CaS inclusions Ca treatment electrolytic extraction thermodynamics three-dimensional investigations

Mild fabrication of SiC/C nanosheets with prolonged cycling stability as supercapacitor

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Journal of Materials science & technology 2022年第15期110卷 178-186页

作者： Shuang Liu Enhui Wang Shichun Liu Chunyu Guo Hailong Wang Tao Yang Xinmei Hou Beijing Advanced innovation center for Materials Genome Engineering Collaborative Innovation Center of Steel TechnologyUniversity of Science and Technology BeijingBeijing 100083China School of Materials science Engineering Zhengzhou UniversityZhengzhou 450001China

A facile and mild route to synthesize C-coated SiC nanosheets(SiC/C NSs)via wet-chemical etching in hydrofluoric acid(HF)at 60°C for 48 h using carbon aluminum silicate(Al_(4)SiC_(4))as raw materials is reported for the first time.HF molecule leads to the breaking of C-Al bonds in Al_(4)SiC_(4),which eventually results in the formation of two-dimensional SiC nanosheets.A carbon layer with a thickness of approximately 1.5 nm is formed on the surface of SiC nanosheets due to the excess carbon.The prepared SiC/C NSs possess a smooth and rectangular sheet with a mean 150 nm in width,500 nm in length and10 nm in thickness,respectively.The crystallographic characterization indicates that 3C-SiC and 2H-SiC coexist and the parallel plane relationship of 3C/2H-SiC heterojunction is(111)_(3C-SiC)//(001)_(2H-SiC).Due to the formed 3C-SiC/2H-SiC heterojunction and graphitic carbon,the fabricated electrode based on SiC/C NSs exhibits prolonged cycling stability and high specific areal capacitance as a promising supercapacitor candidate.It remains 91.2%retention even after 20,000 cycles and 734μF/cm^(2)at a scan rate of 10 m V/s.

关键词： SiC/C nanosheets Al_(4)SiC_(4) Etching Supercapacitors Stability