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Constraint strength and axial/radial particle velocity profiles for an integrated riser outlet

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Particuology 2015年第4期13卷 179-186页

作者： Dewu Wang Chaoyu Yan Chunxi Lu Rui Li Bin Zhao Shaofeng Zhang School of Chemical engineering Hebei University of Technology State Key Laboratory of Heavy Oil Processing China University of Petroleum engineering Research center of Seawater Utilization Technology of Ministry of Education Hebei University of Technology

To study axial/radial profiles of particle velocity in the affected region of an integrated riser outlet, a cold model was developed for the integrated riser reactor combining the gas-solid distributor with the fluidized bed. Constraints, related to the gas-solid distributor and the upper fluidized bed, imposed on the particle flow in the riser outlet region, were investigated experimentally. The experimental results showed that with increasing superficial gas velocity, these constraints have strong influences on particle flow behavior, the particle circulation flux in the riser, and the height of the static bed material of the upper fluidized bed. When the constraints have greater prominence, the axial profile of the cross-sectionally averaged particle velocity in the outlet region initially increases and then decreases, the rate of decrease being proportional to the constraint strength. Along the radial direction of the outlet section, the region where the local particle velocity profile tends to decrease appears near the dimensionless radius r/R = 0.30 initially and then, with increasing constraint strength, gradually extends to the whole section from the inner wall. Based on the experimental data, an empirical model describing the constraint strength was established. The average relative error of the model is within 7.69%.

关键词： Combined fluidized bed Riser Outlet structure Particle velocity Constraint strength

Notably Accelerated Nano-Bainite Transformation via Increasing Undissolved Carbides Content on GCr15Si1Mo Bearing Steel

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 703-712页

作者： Yan-Hui Wang Hua-Qiang Sun Wen-Jing Feng Lei-Jie Zhao Xiang Chen Qing-An Chen Hai-Tao Sun Jian-Jun Wang Zhi-Nan Yang Key Laboratory of Intelligent Industrial Equipment Technology of Hebei Province School of Mechanical and Equipment EngineeringHebei University of EngineeringHandan056038China Collaborative Innovation center for Modern Equipment Manufacturing of Jinan New Area Hebei University of EngineeringHandan056038China School of Materials Science and engineering Tsinghua UniversityBeijing100084China Avic Shang da Superalloys Company Limited Xingtai054800China National engineering Research center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao066004China

In this study, a high-carbon nano-bainitic GCr15Si1Mo bearing steel was investigated. Specifically, the effects of content and size of undissolved carbides on the microstructure and transformation kinetics of nano-bainite were analyzed. The results demonstrated that after prolonged austempering at low temperatures, the mixed microstructure composed of nano-bainite (NB), undissolved carbides (UC), and retained austenite (RA) was obtained in GCr15SiMo steel. When the experimental steel was austenitized at 900 ℃, the undissolved carbides gradually dissolved until reaching a stable state with increasing holding time. Furthermore, at the same austempering temperature, despite different volume fractions of undissolved carbides in the substrate, the volume fractions of nano-bainite in the final microstructures remained essentially the same. Moreover, the higher the content of undissolved carbides in steel, the faster the transformation rate of nano-bainite and the shorter the total transformation time.

关键词： Nano-bainite Undissolved carbides Bainitic transformation kinetics Carbon concentration

Renewable non-edible oils derived long chain (C24.1) bio-based zwitterionic surfactant with ultralow interfacial tension between crude oil and formation brine

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Green Chemical engineering 2023年第3期4卷 346-355页

作者： Homely Isaya Mtui Fang-Hui Liu Wei Wang Jian-Qiao Lang Shi-Zhong Yang Bo-Zhong Mu State Key Laboratory of Bioreactor engineering and School of Chemistry and Molecular engineering East China University of Science and TechnologyShanghai200237China engineering Research center of Microbial Enhanced Oil Recovery Ministry of EducationEast China University of Science and TechnologyShanghai200237China Shanghai Collaborative Innovation center for Biomanufacturing Technology Shanghai200237China

A new ultra-long chain monounsaturated 4-(N-nervonicamidopropyl-N,N-dimethylammonium)butane sulfonate(NDAS)zwitterionic surfactant with ultralow interfacial tensions was developed through the modification of nervonic acid derived from renewable non-edible seed oils by a simple and effective *** structure was characterized by ESI-HRMS,1 H NMR,and 13 C *** surfactant exhibited a strong interfacial activity(~10^(-4) mN/m)between the crude oil and the formation brine at a very low surfactant dosage(0.05 g/L)and at high salinity conditions,which is equivalent to 2%(w/w)of dosage of the most traditional surfactants used in the enhanced oil recovery ***,at a very low concentration(0.05 g/L),NDAS demonstrated strong NaCl compatibility up to 100 g/L,Ca^(2+)ions compatibility up to 200 mg/L,and temperature stability up to 90℃.The surface tension,emulsification,and biodegradability parameters were also *** work consolidates our hypothesis that increasing the hydrophobic chain length of a surfactant certainly contributes to the high interfacial activity and good compatibility of salts and ***,it will facilitate the design of a sustainable alternative to petroleum-based chemicals to develop bio-based surfactants and extend the domain of bio-based surfactants to new applications such as in enhanced oil recovery(EOR).

关键词： Bio-based surfactant Interfacial tension Salt tolerance Enhanced oil recovery Biodegradability

Sufficient conditions for stability of linear time-delay systems with dependent delays

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Journal of Systems engineering and Electronics 2013年第5期24卷 845-851页

作者： Ying Zhu Qina Gao Yang Xiao School of Electronic and Information engineering Beihang University Beijing Aeronautical Technology Research center Institute of Information Science Beijing Jiaotong University

According to the delay property, linear time-delay （LTD） systems can be classified as LTD systems with depen- dent delays （LTD_DD） and LTD systems with independent delays （LTD_ID）. This paper reveals that the stability condition for LTD_ID systems can be applied to LTD_DD systems, a sufficient stability condition for LTD_DD systems is derived from it, while only fewer of the LTD_DD systems can satisfy the stability condition due to the very strict limitation for the delays of the LTD_DD systems. To solve the problem, based on two-dimensional （2-D） hybrid polynomials, some sufficient conditions for stability of LTD_DD systems are pro- posed. Examples show that the proposed stability test algorithms are simple and valid.

关键词： time-delay systems auasipolvnomials stabilitv test

Molecular recognition and biological application of modified β-cyclodextrins

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Science China Chemistry 2019年第5期62卷 549-560页

作者： Ying-Ming Zhang Qiao-Yan Xu Yu Liu College of Chemistry State Key Laboratory of Elemento-Organic ChemistryNankai University Collaborative Innovation center of Chemical Science and engineering (Tianjin)

The molecular recognition based on cyclodextrins(CDs) has become a focus of interest in modern supramolecular *** are known to encapsulate various ions and organic/inorganic molecules in their hydrophobic cavities and form stable inclusion complexes through cooperative noncovalent interactions. During the past few decades, a large variety of modified CDs have been elaborately designed and synthesized, which significantly promotes our molecular-level understanding of the structure–function relationship in many supramolecular systems. Through the accurate analysis on the molecular binding behaviors, one can create a library of CD-based nanoassemblies with controlled physicochemical properties. In this review, we will focus on the stability constant-directed molecular recognition and the biological activities of β-CDs toward some representative bioactive substrates, including metal ions, steroids, porphyrins, amino acids and oligopeptides, as well as drug molecules, with the final goal of promoting their practical applications in the biomedical field.

关键词： Host-guest chemistry molecular recognition cyclodextrin biological function

Mechanical properties and corrosion behavior of selective laser melted 316L stainless steel after different heat treatment processes

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Journal of Materials Science & Technology 2019年第7期35卷 1499-1507页

作者： Decheng Kong Chaofang Dong Xiaoqing Ni Liang Zhang Jizheng Yao Cheng Man Xuequn Cheng Kui Xiao Xiaogang Li Beijing Advanced Innovation center for Materials Genome engineering Key Laboratory for Corrosion and Protection (MOE)Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China Shanghai engineering Research center of 3D Printing Materials Shanghai Research Institute of MaterialsShanghai 200437China School of Materials Science and engineering Ocean University of ChinaQingdao 266100China

Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and corrosion properties of 316 L stainless steel fabricated by selective laser melting. Sub-grains and low-angle boundaries exist in the as-received selective laser melted(SLMed) 316 L stainless steel. After heat treatment at 1050℃, the sub-grains and low-angle boundaries changed slightly, and the stress state and strength decreased to some extent due to the decrease of dislocation density. After heat treatment at 1200℃, the grains became uniform, and the dislocation cells vanished, which led to a sharp decline in the hardness and strength. However, the ductility was improved after recrystallization heat *** passive film thickness and corrosion potential of the SLMed 316 L stainless steel decreased after heat treatment, and the pitting potential also decreased due to the accelerated transition from metastable to steady-state pitting;this accelerated transition was caused by the presence of weak passive films at the enlarged pores after heat treatment, especially for an adequate solid solution treatment.

关键词： 316L stainless steel Selective laser melting Heat treatment Microstructure Mechanical property Corrosion behaviour

Direct low-temperature synthesis of graphene on various glasses by plasma-enhanced chemical vapor deposition for versatile, cost-effective electrodes

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Nano Research 2015年第11期8卷 3496-3504页

作者： Jingyu Sun Yubin Chen Xin Cai Bangjun Ma Zhaolong Chen Manish Kr. Priydarshi Ke Chen Teng Gao Xiuju Song Qingqing Ji Xuefeng Guo Dechun Zou Yanfeng Zhang Zhongfan Liu center for Nanochemistry (CNC) Beijing Science and Engineering Center for Nanocarbons College of Chemistry and Molecular Engineering Peking University Beijing 100877 China Department of Materials Science and engineering College of Engineering Peking University Beijing 100871 China Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Department of Chemistry and Chemical Biology Harvard University Cambridge MA 02138 USA

Catalyst-free and scalable synthesis of graphene on various glass substrates at low temperatures is of paramount significance to numerous applications such as low-cost transparent electronics and state-of-the-art displays. However, systematic study within this promising research field has remained scarce thus far. Herein, we report the direct growth of graphene on various glasses using a low-temperature plasma-enhanced chemical vapor deposition method. Such a facile and scalable approach guarantees the growth of uniform, transfer-free graphene films on various glass substrates at a growth temperature range of 400-600 ℃. The morphological, surface wetting, optical, and electrical properties of the obtained graphene can be tailored by controlling the growth parameters. Our uniform and high-quality graphene films directly integrated with low-cost, commonly used glasses show great potential in the fabrication of multi-functional electrodes for versatile applications in solar cells, transparent electronics, and smart windows.

关键词： graphene direct plasma-enhanced chemical vapor deposition (PECVD) glass various low-cost

Tensile properties of AZ31 sheet/bar and effects of texture

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中国有色金属学会会刊：英文版 2006年第A03期16卷 1741-1745页

作者：周清 G.ITOH Y.MOTOHASHI College of Mechanical and Electrical engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical engineering College of EngineeringIbaraki UniversityHitachi 316-8511Japan Research center For Superplasticity Ibaraki UniversityHitachi 316-8511Japan

For understanding the deformation mechanism of AZ31 Mg alloy, two kinds of specimen, hot-rolled sheet and extruded bar were tested in tension at room temperature. Relatively small grain sizes ranging from 32 to 8.7μm are obtained by annealing at several temperatures. And then they were further cold-rolled with rolling angles of 0? 45?and 90? which is the angle between the rolling and the longitude direction of as-received specimen, and annealed at a temperature in recrystallization field. The yield stress were found from the stress—strain curve. The grain size dependence of the yield stress is found not in agreement with the Hall-Petch relationship. The texture of (0002) pole figure of each kind of specimen was tested by X-ray diffractometer. The specimen with strong basal texture shows large yield stress and low work-hardening rate, while the specimen with weak basal texture shows low yield stress and rapid work-hardening rate. These results are interpreted by the slip system activated in the different textures. A combined slip system was used to interpret the yield stress variation with the texture and the deformation mechanism was discussed.

关键词：镁合金机械性能金属变形张力应变分析

Dynamic mechanical characteristics and application of constant resistance energy-absorbing supporting material

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International Journal of Mining Science and Technology 2022年第3期32卷 447-458页

作者： Qi Wang Shuo Xu Manchao He Bei Jiang Huayong Wei Yue Wang State Key Laboratory for Geo-mechanics and Deep Underground engineering China University of Mining and Technology-BeijingBeijing 100083China Research center of Geotechnical and Structural engineering Shandong UniversityJinan 250061China

In deep underground engineering,rock burst and other dynamic disasters are prone to occur due to stress concentration and energy accumulation in surrounding *** control of dynamic disasters requires bolts and cables with high strength,high elongation,and high energy-absorbing ***,a constant resistance energy-absorbing(CREA)material is *** this study,the dynamic characteristics of the new material are obtained via the drop hammer tests and the Split Hopkinson Pressure Bar(SHPB)tests of the new material and two common bolt(CB)materials widely used in the *** test results of drop hammer test and SHPB test show that the percentage elongation of CREA material is more than 2.64 and 3.22 times those of the CB material,and the total impact energy acting on CREA material is more than 18.50 and 21.84 times,respectively,indicating that the new material has high elongation and high energy-absorbing ***,the CREA bolts and cables using the new material are developed,which are applied in roadways with high stress and strong dynamic *** field monitoring results show that CREA bolts and cables can effectively control the surrounding rock deformation and ensure engineering safety.

关键词： Constant resistance energy-absorbing Supporting material Dynamic impact tests Mechanical characteristics Field application