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Reaction kinetics and mechanism of biomass pyrolysis in a micro-fluidized bed reactor

Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology 2010年第6期38卷 666-672页

作者： Yu, Jian Zhu, Jian-Hong Guo, Feng Duan, Zheng-Kang Liu, Yun-Yi Xu, Guang-Wen State Key Laboratory of Multi-phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Chemical Engineering Institute of Xiangtan University Xiangtan 411105 China School of Chemical Engineering Shenyang Institute of Chemical Technology Shenyang 110142 China

A Micro Fluidized Bed Reaction Analyzer (MFBRA) was used to study the pyrolysis of biomass in argon. Through on-line pulse feeding of reactant and continuously monitoring the composition changes of gas product, the MFBRA enables the measurement of reaction rates at arbitrary temperatures, the deduction of kinetic parameters and the analysis of reaction mechanism. By applying to biomass pyrolysis this article found that the pyrolysis reaction can finish in about 10s, which is much shorter than the other literature values obtained in larger fluidized bed reactors but very close to the theoretically anticipated values. The detected evolving sequences of different gas species and the deduced kinetic parameters demonstrate further that the reactions between/among the formed different gas species in pyrolysis prevail to certain degree and there are different pathways for forming the different gas species. The activation energy and pre-exponential factor derived by treating the pyrolysis gas as a single product are 11.77 kJ/mol and 1.45s-1, which are obviously lower than the literature values measured in thermogravimetric analyzers.

关键词： Fluidized beds

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Role of Black Carbon in Modulating Aerosol Direct Effects Driven by Air Pollution Controls During 2013-2017 in China

SSRN

引用

SSRN 2022年

作者： Zhang, Fenfen Xing, Jia Ding, Dian Wang, Jiandong Zheng, Haotian Zhao, Bin Qi, Ling Wang, Shuxiao State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing100084 China Institute for Atmospheric and Earth System Research Faculty of Science University of Helsinki Helsinki00014 Finland School of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing210044 China School of Energy and Environmental Engineering University of Science and Technology Beijing Beijing100083 China

Aerosol direct effects (ADEs) can modulate shortwave radiation as well as atmospheric dynamics and air quality. As the key absorbing component of aerosol, the black carbon (BC) largely determines the aerosol optical properties. Therefore, it is expected that BC emission controls might gain co-benefits from the simultaneous reduction of ADEs. To demonstrate such synergy, we quantified the ADEs changes and role of BC controls in China during 2013-2017 using a regional two-way coupled meteorology chemistry transport model. Results suggest that the control action effectively reduced wintertime PM2.5 concentration (-26.0 μg m-3) and associated ADEs. The influence of ADEs on surface shortwave radiation, 2-meter temperature, and planetary boundary layer height was weakened from -16.7 W m-2, -0.20°C, and -15.4 m in 2013 to -11.3 W m-2, -0.06°C, and -10.7 m in 2017, respectively. The enhancement of SO2, NO2, and PM2.5 concentrations due to ADEs was reduced from +3.1%, +5.2%, and +5.4% in 2013, to +2.6%, +4.5%, and +3.3% in 2017, respectively, demonstrating the extra benefit of air pollution controls by reducing ADEs. The BC emission reduced by 12.5% simultaneously along with the effective controls during 2013-2017. Such BC controls contributes 15.6-60.2% of such changes in the ADEs influence on meteorological variables, and 32.6-41.1% on air pollutants. More specially, the effectiveness of collaborative reduction of BC further reduced surface shortwave radiation in China by 3.6 W m-2 in January and 1.0 W m-2 in July, leading to a more weakened ADEs that bring extra benefits in reducing PM2.5 concentrations by 1.8 μg m-3 in January and 0.3 μg m-3 in July. Apparently, BC played a dominant role in modulating the ADEs and associated influences on meteorology and air quality, suggesting a wise control strategy by targeting absorbing component of PM2.5 reduction to address both air pollution and climate change in the future. © 2022, The Authors. All rights reserved.

关键词： Air quality

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Linear building pattern recognition via spatial knowledge graph

arXiv

引用

arXiv 2023年

作者： Wei, Zhiwei Xiao, Yi Tong, Ying Xu, Wenjia Wang, Yang Key Laboratory of Network Information System Technology Institute of Electronic Chinese Academy of Sciences Beijing 100830 The Aerospace Information Research Institute Chinese Academic of Sciences Beijing 100830 School of Resources and Environment Science Wuhan University Wuhan 430079 School of Software Engineering Shenzhen Institute of Information Technology Guangdong Shenzhen 518172 School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876

Building patterns are important urban structures that reflect the effect of the urban material and social-economic on a region. Previous researches are mostly based on the graph isomorphism method and use rules to recognize building patterns, which are not efficient. The knowledge graph uses the graph to model the relationship between entities, and specific subgraph patterns can be efficiently obtained by using relevant reasoning tools. Thus, we try to apply the knowledge graph to recognize linear building patterns. First, we use the property graph to express the spatial relations in proximity, similar and linear arrangement between buildings;secondly, the rules of linear pattern recognition are expressed as the rules of knowledge graph reasoning;finally, the linear building patterns are recognized by using the rule-based reasoning in the built knowledge graph. The experimental results on a dataset containing 1289 buildings show that the method in this paper can achieve the same precision and recall as the existing methods;meanwhile, the recognition efficiency is improved by 5.98 times. © 2023, CC BY.

关键词： Buildings

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Parallel Hospital: ACP-Based Hospital Smart Operating system

Parallel Hospital: ACP-Based Hospital Smart Operating System

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Digital Twins and Parallel Intelligence (DTPI), IEEE International Conference on

作者： Yongjun Wang Fei-Yue Wang Xiao Wang Zhongjun Guan Liwei Ouyang Jiangong Wang Lan Yan Wenbo Zheng Wenwen Zhang Beijing Tiantan Hospital Capital Medical University Beijing Beijing China The State Key Laboratory for Management and Control of Complex Systems Institute of Automation Chinese Academy of Sciences Beijing China Qingdao Academy of Intelligent Industries Qingdao China School of Artificial Intelligence University of Chinese Academy of Sciences Beijing China School of Software Engineering Xi'an Jiaotong University Xi'an China

This article aims to propose a parallel hospital based on parallel medicine. The parallel hospital takes the parallel idea of virtual and real interaction as its core concept and uses parallel idea's artificial scenarios, computational experiments, and parallel execution (ACP) theory as the guiding theory to construct a new generation of intelligent hospital management system with virtual and real interaction. We conducted a case study of the parallel hospital practice case of Tiantan Hospital-Tiantan Smart Brain, so as to confirm the feasibility and scientificity of the proposed parallel hospital.

关键词： Training Hospitals Operating systems Digital twin Conferences

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An integrated framework for accelerating reactive flow simulation using GPU and machine learning models

arXiv

引用

arXiv 2023年

作者： Mao, Runze Wang, Yingrui Zhang, Min Li, Han Xu, Jiayang Dong, Xinyu Zhang, Yan Chen, Zhi X. State Key Laboratory of Turbulence and Complex Systems Aeronautics and Astronautics College of Engineering Peking University Beijing100871 China Beijing100080 China Shanghai SenseTime Intelligent Technology Co. LTD Shanghai200233 China CAEP Software Center for High Performance Numerical Simulation Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Recent progress in artificial intelligence (AI) and high-performance computing (HPC) have brought potentially game-changing opportunities in accelerating reactive flow simulations. In this study, we introduce an open-source computational fluid dynamics (CFD) framework that integrates the strengths of machine learning (ML) and graphics processing unit (GPU) to demonstrate their combined capability. Within this framework, all computational operations are solely executed on GPU, including ML-accelerated chemistry integration, fully-implicit solving of PDEs, and computation of thermal and transport properties, thereby eliminating the CPU-GPU memory copy overhead. Optimisations both within the kernel functions and during the kernel launch process are conducted to enhance computational performance. Strategies such as static data reorganisation and dynamic data allocation are adopted to reduce the GPU memory footprint. The computational performance is evaluated in two turbulent flame benchmarks using quasi-DNS and LES modelling, respectively. Remarkably, while maintaining a similar level of accuracy to the conventional CPU/CVODE-based solver, the GPU/ML-accelerated approach shows an overall speedup of over two orders of magnitude for both cases. This result highlights that high-fidelity turbulent combustion simulation with finite-rate chemistry that requires normally hundreds of CPUs can now be performed on portable devices such as laptops with a medium-end GPU. © 2023, CC BY.

关键词： Graphics processing unit

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Delamination of an Elastic Cuboid from a Flat Rigid Substrate

SSRN

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SSRN 2023年

作者： Chen, ZiJian Sun, XiaoHao Zhu, YinBo He, ZeZhou Zhao, Yang Wang, Zhengzhi Wu, HengAn Wu, XiaoPing Gu, Ping CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei230027 China Department of Mechanical Engineering University of Colorado Boulder BoulderCO80309 United States Department of Precision Machinery & Precision Instrumentation University of Science and Technology of China Hefei230026 China Department of Engineering Mechanics School of Civil Engineering Wuhan University Hubei Wuhan430072 China

Due to their strong pull-off force on noncooperative objects, dry adhesive materials have promising applications in gecko-mimicking robots and mechanical grippers. Previous experimental studies have shown that uniform interfacial stress and center delamination are favorable for achieving a high pull-off force;however, an in-depth understanding of interfacial stress distribution, delamination mode, and pull-off force of square cross-section elastomers is lacking. The square cross-section is expected to improve the packing ratio and pull-off force further. This paper studies a model system where an elastic square cuboid is detached from a flat rigid substrate to provide theoretical support for the design of adhesive materials. Based on elastomers' energy release rate and instability, we establish a three-dimensional model for the elastic square cuboid and analyze the mechanism of three delamination modes: edge delamination, center delamination, and cavity delamination. Furthermore, a new theoretical model for the pull-off force and phase diagram of the various delamination modes is developed. We found three subdivision crack patterns in the cuboid edge delamination mode, arc-shaped, fingering, and rhombus, which are different from the cylinder sample. Fingering cracks of cylinder samples are usually considered characteristics of elastic instability, but those of cuboid samples cannot be defined as elastic instability. The three edge crack patterns are gradually transformed, determined by the interfacial stress distribution, which is affected by the sample width-to-thickness ratio. The following results are obtained by combining the experimental and theoretical pull-off forces and phase diagram data. First, the interfacial stress distribution determines the pull-off force, and the delamination mode is an index to judge the stress distribution. Second, we propose a novel dry adhesive design strategy that regulates interfacial delamination to achieve controllable pull-of

关键词： Adhesion

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Exploration of a Novel Method for Thyroid Nodule Ultrasound Image Segmentation

Exploration of a Novel Method for Thyroid Nodule Ultrasound ...

引用

International Congress on Image and Signal Processing, BioMedical engineering and Informatics (CISP-BMEI)

作者： Kai He Yuan Li Ting Li Xiao Sun Mei Wu Wei Guo Xian Zhao Zhi Liu Key Laboratory of Laser and Infrared System of the Ministry of Education Shandong University Qingdao China Department of Thoracic Surgery The Second Hospital Cheeloo College of Medicine Shandong University Jinan China Department of Ultrasound Qilu Hospital of Shandong University Jinan China School of Software Shandong University Jinan China School of Information Science and Engineering Shandong University Qingdao China

ISBN: (数字)9798331507398

ISBN: (纸本)9798331507404

Ultrasound examination of thyroid nodules is currently the mainstream method for diagnosing thyroid diseases. Segmentation of thyroid nodule ultrasound images is a cru-cial task in computer-aided diagnosis of thyroid nodules and holds significant importance in the entire diagnostic process. However, due to the complex features and low contrast of thyroid ultrasound images, traditional semantic segmentation algorithms struggle to extract effective features, making it dif-ficult to accurately identify the nodule regions and complete the segmentation task. To address these issues and advance research in thyroid nodule segmentation, this paper proposes a deep learning model for accurate identification and high-quality segmentation of nodule regions in thyroid nodule segmentation. To demonstrate the effectiveness of our method, we collected ultrasound images from clinical examinations at the Second Hospital of Shandong University to serve as our experimental dataset. Evaluations conducted on this dataset show that our method achieves outstanding performance compared to existing mainstream algorithms.

关键词： Image segmentation Ultrasonic imaging Hospitals Semantic segmentation Signal processing algorithms Signal processing Feature extraction Informatics Thyroid Diseases

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Electrochemistry Properties of Multilayer TiN/Ti Coatings on NiTi Alloy for Cardiac Occluder Application

Electrochemistry Properties of Multilayer TiN/Ti Coatings on...

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The 8th Asian-European International Conference on Plasma Surface engineering 第八届亚欧国际等离子体表面工程会(AEPSE2011)

作者： Y.Cheng A.L.Shao T.F.Xi Y.F.Zheng Y.B.Wang Y.Zhou Biomedical Engineering Research center Shenzhen Institution of Peking UniversityShenzhen 518057China Biomedical Engineering Research centerShenzhen Institution of Peking UniversityShenzhen 518057China Biomedical Engineering Research centerShenzhen Institution of Peking UniversityShenzhen 518057China State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology College of EngineeringPeking UniversityBeijing 100871China Center for Biomedical Materials and Tissue Engineering Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing 100871China

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MetAug: Contrastive Learning via Meta Feature Augmentation

arXiv

引用

arXiv 2022年

作者： Li, Jiangmeng Qiang, Wenwen Zheng, Changwen Su, Bing Xiong, Hui Science & Technology on Integrated Information System Laboratory Institute of Software Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Guangdong China Gaoling School of Artificial Intelligence Renmin University of China Beijing China Beijing Key Laboratory of Big Data Management and Analysis Methods Beijing China Guangzhou China Department of Computer Science Engineering The Hong Kong University of Science and Technology Hong Kong

What matters for contrastive learning? We argue that contrastive learning heavily relies on informative features, or "hard" (positive or negative) features. Early works include more informative features by applying complex data augmentations and large batch size or memory bank, and recent works design elaborate sampling approaches to explore informative features. The key challenge toward exploring such features is that the source multi-view data is generated by applying random data augmentations, making it infeasible to always add useful information in the augmented data. Consequently, the informativeness of features learned from such augmented data is limited. In response, we propose to directly augment the features in latent space, thereby learning discriminative representations without a large amount of input data. We perform a meta learning technique to build the augmentation generator that updates its network parameters by considering the performance of the encoder. However, insufficient input data may lead the encoder to learn collapsed features and therefore malfunction the augmentation generator. A new margin-injected regularization is further added in the objective function to avoid the encoder learning a degenerate mapping. To contrast all features in one gradient back-propagation step, we adopt the proposed optimization-driven unified contrastive loss instead of the conventional contrastive loss. Empirically, our method achieves state-of-the-art results on several benchmark datasets. Copyright © 2022, The Authors. All rights reserved.

关键词： Backpropagation

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Optimized modeling of signalized intersections coordination based on two-way bandwidth maximization

引用

Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (engineering and Technology Edition) 2009年第SUPPL. 2期39卷 19-24页

作者： Ma, Nan Shao, Chun-Fu Zhao, Yi Key Laboratory of Urban Transportation Complex System Theory and Technology Ministry of Education Beijing Jiaotong University Beijing 100044 China Department of Civil and Environmental Engineering University of Nevada Reno Reno NV89557 United States

To reduce traffic delays, relieve congestion, and improve the operation of urban traffic network, a phase sequence optimization model was presented based on the idea of maximization of two-way green wave bandwidth. Under 15 difference groups of scenarios, VISSIM was used for testifying the effectiveness of the optimization model. The simulation results show that the optimized scheme reduces the intersection delay by 2%-29%, the number of stops by 14%-28% and travel time by 1%-9%, which greatly improves the operation condition of urban road network.

关键词： Bandwidth

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