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Distribution of phytoplankton community and its influence factors in an urban river network,East China

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Frontiers of Environmental Science & Engineering 2018年第6期12卷 133-144页

作者： Ling Sun Hui Wang Yuanqing kan Shiliang Wang State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Tianjin Key Laboratory of Animal and Plant Resistance College of Life SciencesTianjin Normal UniversityTianjin 300387China Tianjin Academy of Environmental Sciences Tianjin 300191China School of Geography and Tourism Qufu Normal UniversityRizhao 276826China

To reveal the distribution characteristics of phytoplankton and the main influence factors under different conditions in the urban rivers, the investigations were conducted during autumn and winter 2014 in Changzhou City, East China. 178 taxa of phytoplankton belonging to 28 functional assemblages were identified. In autumn, the phytoplankton community compositions have high similarity for enhanced hydrological connectivity. The chlorophytes and diatoms (prevailing functional groups C, F, J, P), together with euglenoids (W1), showed high proportions of biomass in the main rivers and connected rivers. It was related to the well mixed eutrophic conditions. The phytoplankton community exhibited spatiotemporal heterogeneity in winter. Affected by the low water level and temperature, the free-living phytoflagellates (X2) replaced groups F and J in the main rivers. Phytoplankton productivity was the highest in the Tongji River. Chlorophytes Dictyosphaerium ehrenbergianum and Chlamydobotrys stellata had an overwhelming superiority during the winter bloom. They were significantly correlated with ammonium, total phosphorus and biochemical oxygen demand. Affected by tail water supply, the diatoms (MP) and euglenoids (W1) dominated in a beheaded river. The multivariate analyses based on the phytoplankton functional groups helped to evaluate the relationships and variations between the urban rivers. The redundancy analysis (RDA) results showed that nitrate nitrogen, water temperature, total nitrogen and total suspended solids were the main influence factors on the phytoplankton community. Except MP, the prevailing groups all showed significant negative correlations with nitrate nitrogen. Availability and utilization of dissolved inorganic nitrogen and hydrodynamic conditions affected the phytoplankton distribution.

关键词： Phytoplankton composition Spatiotemporal distribution Functional groups Nitrate nitrogen Winter bloom

Effects of End-Bend and Curved Blades on the Flow Field and Loss of a Compressor Linear Cascade in the Design Condition

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Journal of Thermal Science 2019年第4期28卷 801-810页

作者： kan Xiaoxu WU Wanyang YAng Ling ZHOng Jingjun Merchant Marine College Shanghai Maritime University

Curved blade and end-bend blade are considered as effective passive control methods for improving the aerodynamic performance of a compressor cascade,and their applicability also needs to be further studied.A highly-loaded compressor linear cascade in the design condition was taken as the research objective in this *** simulation was used to study the positive and negative effects of these methods on the flow loss of the cascade by redistributing the vortex *** show that:the curved blade could reduce the flow loss to 2.55%,while the end-bend blade and the end-bend+curved blade increase it to 10.58%and 2.19%,*** positive effect of the curved blade weakens the strength and scale of Concentrated Shedding Vortex(CSV),which accounts for 59.2%of the total flow *** negative effect of the end-bend blade exacerbates the low-energy fluid clusters from the end wall and wake into ***,the end-bend+curved blade can take their own strengths,but it enhances the twisting motion of Passage Vortex(PV)and CSV,which makes it fail to reduce the flow ***,the positive and negative effects of these methods on the flow loss of a compressor cascade are much *** addition,we also predict the potential danger of the end-bend blade in the negative incidence conditions and provides some suggestion for future study.

关键词： compressor linear cascade flow loss vortex structure curved blade end-bend blade design condition

Experimental study and electromechanical model analysis of the nonlinear deformation behavior of IPMC actuators

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Acta Mechanica Sinica 2017年第2期33卷 382-393页

作者： Hongguang Liu Ke Xiong kan Bian Kongjun Zhu State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Faculty of Civil Engineering and Mechanics Jiangsu University

This paper develops analytical electromechanical formulas to predict the mechanical deformation of ionic polymer-metal composite (IPMC) cantilever actuators under DC excitation voltages. In this research, IPMC samples with Pt and Ag electrodes were manufactured, and the large nonlinear deformation and the effect of curvature on surface electrode resistance of the IPMC samples were investigated experimentally and theoretically. A distributed electrical model was modified for calculating the distribution of voltage along the bending actuator. Then an irreversible thermodynamic model that could predict the curvature of a unit part of an IPMC actuator is combined with the electrical model so that an analytical electromechanical model is developed. The electromechanical model is then validated against the experimental results obtained from Pt- and Ag-IPMC actuators under various excitation voltages. The good agreement between the electromechanical model and the actuators shows that the analytical electromechanical model can accurately describe the large nonlinear quasi-static deflection behavior of IPMC actuators.

关键词： Actuator Ionic polymer metal composite Nonlinear deformation Electromechanical model

Refinement and migrating behaviors in Al-Si hypereutectic alloys solidified under electromagnetic vibration

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Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 301-308页

作者： Jianbo YU Zhongming REN kan9 DEng Shanghai Enhanced Laboratory of Ferro-Metallurgy Shanghai University Shanghai 200072 China

The effects of electromagnetic vibration （EMV） on the refinement and migration of primary silicons in the A1-18 wt pct Si alloy were investigated systematically. It was found that EMV could effectively refine primary silicons. The equivalent diameter of primary silicon first decreases slowly with the current increasing from 1 A to 3 A, but then drops rapidly between 3 A and 10 A, next gradually decreases with increasing current intensity. When the EMV intensity was low, the primary silicons were agglomerated and expelled to the top of a sample, the segregation of silicon grains gradually decreased and the agglomerating phenomena disappeared with the increase of EMV intensity, and the star-like coarse primary silicons turned refined flake or square morphology. The refinement and migration of primary silicons depended on the Lorentz force, gravity and the effective viscous force.

关键词： High magnetic field Electromagnetic vibration HypereutecticAl-Si alloys Primary silicon Refinement Migrating

Developing silicon-based photocathodes for CO_(2) conversion

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Science China Chemistry 2024年第6期67卷 1904-1921页

作者： Weijie Zhuang Miao kan Tao Meng Jinlong Zhang Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237China Shanghai Engineering Research Center for Multimedia Environmental Catalysis and Resource Utilization East China University of Science and TechnologyShanghai200237China

Photoelectrochemical(PEC)conversion of CO_(2) presents a promising avenue for solar-driven chemical fuel production,with silicon emerging as a cost-effective and high-light-absorbing material pivotal to this *** at exploring opportunities for industrializing PEC CO_(2) reduction(PEC-CO_(2)R)by minimizing reaction energy consumption,enhancing reaction efficiency and selectivity,this review summarizes recent advancements in developing Si-based photocathodes for PEC-CO_(2)*** outlines the fundamental principles,advantages,and limitations of Si photocathodes with key performance *** on this understanding,the strategies to enhance the performance of the PEC-CO_(2)R system,including light absorption,charge separation,and catalytic reactions are categorized as the interfacial modification,active site decoration,and protective layer *** design ideas of this advantageous three-layer structure in promoting the efficiency,stability,and selectivity have been ***,this review scrutinizes the influence of the photocathodic chemical *** review consolidates the mechanism insights and notable breakthroughs of various fuel generation processes within Si-based PEC-CO_(2)R *** this wealth of information offers an up-to-date perspective on the dynamic developments in silicon-based PEC-CO_(2) conversion and underscores the promising pathways toward the sustainable fuel synthesis from pollutant CO_(2).

关键词： photoelectrochemistry solar fuels silicon photocathodes carbon dioxide reduction microenvironment

Highly Optimized Code Generation for Stencil Codes with Computation Reuse for GPUs

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Journal of Computer Science & Technology 2016年第6期31卷 1262-1274页

作者： Wen-Jing Ma kan Gao Guo-Ping Long Laboratory of Parallel Software and Computing Science Institute of Software Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Beijing 100190 China Information Center China Association for Science and Technology Beijing 100863 China

Computation reuse is known as an effective optimization technique. However, due to the complexity of modern GPU architectures, there is yet not enough understanding regarding the intriguing implications of the interplay of compu- ration reuse and hardware specifics on application performance. In this paper, we propose an automatic code generator for a class of stencil codes with inherent computation reuse on CPUs. For such applications, the proper reuse of intermediate results, combined with careful register and on-chip local memory usage, has profound implications on performance. Current state of the art does not address this problem in depth, partially due to the lack of a good program representation that can expose all potential computation reuse. In this paper, we leverage the computation overlap graph （COG）, a simple representation of data dependence and data reuse with ＂element view＂, to expose potential reuse opportunities. Using COG, we propose a portable code generation and tuning framework for GPUs. Compared with current state-of-the-art code generators, our experimental results show up to 56.7% performance improvement on modern GPUs such as NVIDIA C2050.

关键词： GPGPU OpenCL stencil code generation computation reuse

Investigation of the Vortex Dynamic Mechanism of the Flow Losses on a Transonic Compressor Stator

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Journal of Thermal Science 2019年第1期28卷 51-60页

作者： kan Xiaoxu WAng Songtao LUO Lei SU Jiexian School of Energy Science and Engineering Harbin Institute of Technology

For a transonic axial-flow compressor, the numerical simulations, verified against experimental data, were used to study the inherent correlation between the evolutionary process of the vortex structures and the flow loss in a compressor stator passage during the throttling process. The flow loss was divided accurately and quantitatively, based on the evolutionary process of the vortex structures. According to the position of the singular points of the vortex structures, the influence of the evolution of the vortex structures on the generation and development of the flow loss was analyzed on a microscale scale. Thereafter, this paper provided the vortex dynamic mechanism of the flow loss, which was important to enrich the theoretical system of the flow field in the compressor. The results show that: the flow loss at the top of the stator tip is caused by the low-energy fluid clusters, which are transported and accumulated by the vortices from the endwall; the transport effect of the pressure separation vortex at the upper half-height only migrates the position of the flow losses, but there is new flow loss generated by its shear action to the endwall. The dominant flow loss during the throttling process concentrates upon the closed separation bubble around the middle of the suction side of the stator.

关键词： transonic compressor stator throttling process vortex structure flow losses topological analysis

Overview of particulate air pollution and human health in China: Evidence, challenges, and opportunities

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The Innovation 2022年第6期3卷 39-51页

作者： Qingli Zhang Xia Meng Su Shi Lena kan Renjie Chen Haidong kan School of Public Health Key Lab of Public Health Safety of the Ministry of Education and NHC Key Lab of Health Technology AssessmentShanghai Institute of Infectious Disease and BiosecurityFudan UniversityShanghai 200032China Bloomberg School of Public Health Johns Hopkins UniversityBaltimoreMarylandMD 21205USA Children’s Hospital of Fudan University National Center for Children’s HealthShanghai 201102China

Ambient particulate matter(PM)pollution in China continues to be a major public health *** the release of the new WHO air quality guidelines in 2021,there is an urgent need for China to contemplate a revision of air quality standards(AQS).In the recent decade,there has been an increase in epidemiological studies on PM in China.A comprehensive evaluation of such epidemiological evidence among the Chinese population is central for revision of the AQS in China and in other developing countries with similar air pollution *** thus conducted a systematic review on the epidemiological literature of PM published in the recent decade.

关键词： pollution template revision

Towards Energy Efficient Shape Rolling:Roll Pass Optimal Design and Case Studies

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Chinese Journal of Mechanical Engineering 2019年第3期32卷 78-88页

作者： kan Huang Bin Huang Lei Fu Kazem Abhary School of Civil Engineering Changsha University of Science and TechnologyChangsha 410114China School of Engineering University of South AustraliaAdelaideSouth Australia 5095Australia

Shape rolling is widely employed in the production of long workpieces with appropriate cross-section profiles for other industrial applications. In the development of shape rolling systems, roll pass design (RPD) plays an essential role on the quality control of products, service life of rolls, productivity of rolling systems, as well as energy consumption of rolling operations. This study attempts to establish a generic strategy based on hybrid modeling and an improved genetic algorithm, to support the optimizations of RPD and shape rolling operations at a systematic perspective. Objectives include improving the quality and efficiency of RPD, reducing energy consumption of shape rolling, as well as releasing the demands on costly trails and expert knowledge in RPD. Hybrid modeling based on cross-disciplinary knowledge is developed to overcome the limitations of isolated single-disciplinary models. And conventional genetic algorithm is improved for the implementation of optimal design. Targeting to integrate empirical data and published reliable solutions into optimizations, a parameters estimation method is proposed to transfer the initially misaligned models into a uniform pattern. A tool based on the Matlab platform is developed to demonstrate the optimal design operations, with case studies involved to validate the proposed methodology.

关键词： Roll pass optimal design Hybrid modelling Genetic algorithm Parameters estimation