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Torque model of hydro turbine with inner energy loss characteristics

Science China(Technological Sciences) 2010年第10期53卷 2826-2832页

作者： ZeNG Yun1,2, GUO YaKun2, ZHANG LiXiang1, XU TianMao3 & DONG HongKui4 1 Construction engineering College, Kunming university of Science and Technology, Kunming 650051, China 2 school of engineering, university of aberdeen, aberdeen ab24 3.e, uk 3 Computing Center, Kunming university of Science and Technology, Kunming 650051, China 4 Hydraulic energy Department, Yunnan electric Power Test and Research Institute, Kunming 650217, China Construction engineering College Kunming University of Science and Technology Kunming China school of engineering University of Aberdeen Aberdeen UK Computing Center Kunming University of Science and Technology Kunming China Hydraulic energy Department Yunnan Electric Power Test and Research Institute Kunming China

This paper presents the result and analysis of the composition of energy loss occurring in the hydro turbine. Two new types of energy losses,namely the hydraulic loss in the flow channel and the impact loss,are defined. All losses within the hydro turbine are divided into four types and the loss coefficients are defined accordingly. expressions or characteristic descriptions of these losses as well as the calibration method of the loss coefficients are presented. Furthermore,the torque model of the hydro turbine where the inner energy loss takes place is established. The developed model has been used to calculate the power loss due to the mechanical friction generated by the units’ rotation to solve the difficulty of measurements of the mechanical friction loss in the hydro turbine. The definition of the impact loss explains the phenomenon that the loss of no-load is greater than that of the rated operation. A set of conversion coefficients are defined using the characteristic parameters at the rated operation,which are used to transform the parameters in the torque model into those that are easily measured. Therefore,the expression of the hydro turbine power is converted into a function that has the main servomotor displacement as its single variable. This makes the proposed model be convenient to use. Finally,the proposed model and methods are calibrated and verified using the measured data of a hydropower plant. Good agreement between the modeled results and the measurements indicates that the proposed model can represent the inner energy loss characteristics of the hydro turbine.

关键词： hydraulic loss in flow channel impact loss loss coefficients conversion coefficients

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SOMe NeW DATA AND FORMULAS FOR ReSISTANCe FLOW IN FLUVIAL OPeN CHANNeLS

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Journal of Hydrodynamics 2011年第4期23卷 527-534页

作者： YANG Sheng-fa HU Jiang LI Dan-xun WANG Xing-kui GUO Yakun Department of River and Ocean Chongqing Jiaotong University Chongqing 400074 China State Key Laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China school of engineering University of Aberdeen Aberdeen AB24 3UE UK

Flow resistance in fluvial open channels, especially in steep gravel-bed channels, still presents challenges to researchers and engineers. This article presents some new data from both the flume experiments and field measurements. Data analysis using the divided hydraulic radius approach shows that the relative roughness plays a significant role in the bed form resistance. A new set of formulas that incorporate the relative roughness are proposed. As compared with several existing formulas, the proposed formulas can be used to better estimate the bed form resistance.

关键词： open channel flow flow resistance relative roughness steep gravel-bed flume experiments field measurements

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Stochastic Computing Convolutional Neural Network Architecture Reinvented for Highly efficient Artificial Intelligence Workload on Field-Programmable Gate Array

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Research 2024年第2期2024卷 55-79页

作者： Yang Yang Lee Zaini abdul Halim Mohd Nadhir ab Wahab Tarik Adnan Almohamad school of electrical and electronic engineering Universiti Sains MalaysiaNibong Tebal 14300 Penang Malaysia school of Computer Sciences Universiti Sains MalaysiaGelugor11800 PenangMalaysia electrical-electronics engineering Department Faculty of EngineeringKarabuk University78050 KarabukTurkiye

Stochastic computing(SC)has a substantial amount of study on application-specific integrated circuit(ASIC)design for artificial intelligence(AI)edge computing,especially the convolutional neural network(CNN)***,SC has little to no optimization on field-programmable gate array(FPGA).Scaling up the ASIC logic without FPGA-oriented designs is inefficient,while aggregating thousands of bitstreams is still challenging in the conventional *** research has reinvented several FPGA-efficient 8-bit SC CNN computing architectures,i.e.,SC multiplexer multiply-accumulate,multiply-accumulate function generator,and binary rectified linear unit,and successfully scaled and implemented a fully parallel CNN model on Kintex7 *** proposed SC hardware only compromises 0.14%accuracy compared to binary computing on the handwriting Modified National Institute of Standards and Technology classification task and achieved at least 99.72%energy saving per image feedforward and 31?more data throughput than modern *** to SC,early decision termination pushed the performance baseline exponentially with minimum accuracy loss,making SC CNN extremely lucrative for AI edge computing but limited to classification *** SC's inherent noise heavily penalizes CNN regression performance,rendering SC unsuitable for regression tasks.

关键词： hardware Highly rendering

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experimental study of dynamic mechanical properties of reactive powder concrete under high-strain-rate impacts

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Science China(Technological Sciences) 2010年第9期53卷 2435-2449页

作者： JU Yang1,2,LIU HongBin1,SHeNG GuoHua1,3 & WANG HuiJie1 1 State Key Laboratory of Coal Resources and Safe Mining,Beijing Key Laboratory of Fracture and Damage Mechanics of Rocks and Concrete,China university of Mining and Technology,Beijing 100083,China 2 Department of Mechanical and Manufacturing engineering,university of Calgary,2500 university Drive,ab T2N 1N4,Canada 3 school of Resources and Civil engineering,Northeastern university,Shenyang 110004,China State Key Laboratory of Coal Resources and Safe Mining Beijing Key Laboratory of Fracture and Damage Mechanics of Rocks and Concrete China University of Mining and Technology Beijing China Department of Mechanical and Manufacturing engineering University of Calgary Calgary Canada school of Resources and Civil engineering Northeastern University Shenyang China

The dynamic mechanical properties of reactive powder concrete subjected to compressive impacts with high strain rates ranging from 10 to 1.1×102 s-1 were investigated by means of SHPB (split-Hopkinson-pressure-bar) tests of the cylindrical specimens with five different steel fiber volumetric *** properties of wave stress transmission,failure,strength,and energy consumption of RPC with varied fiber volumes and impact strain rates were *** influences of impact strain rates and fiber volumes on those properties were characterized as *** general forms of the dynamic stress-strain relationships of RPC were modeled based on the experimental *** investigations indicate that for the plain RPC the stress response is greater than the strain response,showing strong brittle *** RPC with a certain volume of fibers sustains higher strain rate impact and exhibits better deformability as compared with the plain *** a constant fiber fraction,the peak compressive strength,corresponding peak strain and the residual strain of the fiber-reinforced RPC rise by varying amounts when the impact strain rate increases,with the residual strain demonstrating the greatest *** the fiber content makes trivial contribution to improving the residual deformability of RPC when the impact strain rate is *** tests also show that the fiber content affects the peak compressive strength and the peak deformability of RPC in a different *** a constant impact strain rate and the fiber fraction less than 1.75%,the peak compressive strength rises with an increasing fiber *** peak compressive strength tends to decrease as the fiber volume exceeds 1.75%.The corresponding peak strain,however,incessantly rises with the increasing fiber *** total energy edisp that RPC consumed during the period from the beginning of impacts to the time of residual strains elevates with the fiber volume increment as long as the fiber fraction

关键词： impact reactive powder concrete (RPC) high strain rate dynamic strength energy consumption dynamic stress-strain response

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Introduction to the Special Issue on Computer-Aided Uncertainty Modeling and Reliability evaluation for Complex engineering Structures

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Computer Modeling in engineering & Sciences 2024年第10期141卷 1-5页

作者： Debiao Meng abílio Manuel Pinho de Jesus Zeng Meng school of Mechanical and electrical engineering University of Electronic Science and Technology of ChinaChengdu611731China INeGI Faculty of EngineeringUniversity of PortoPorto4200-465Portugal school of Civil engineering Hefei University of TechnologyHefei230009China

1 Summary With the advancement of science and technology,complex engineering structures are widely used in extreme environments[1].In equipment service,many uncertainty factors significantly affect safety and reliability[2–5].Therefore,ensuring high reliability of structures has become an important research direction in engineering *** the same time,the importance of equipment health management of complex engineering structures is becoming increasingly prominent[6–8].Computer-aided uncertainty modeling and reliability assessment have become key tools,and finite element simulation and algorithmic innovation play a key role in the reliability analysis of complex equipment[9,10].These techniques can accurately simulate stress and damage accumulation under various operating environments,providing engineers with important decision support and optimization solutions.

关键词： extreme Reliability environments

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Kinetic theory of self-condensing vinyl polymerization

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Science China Chemistry 2010年第12期53卷 2429-2439页

作者： ZHOU ZhiPing 1 & YAN DeYue 2 1 school of Materials Science and engineering,Jiangsu university,Zhenjiang 212013,China 2 school of Chemistry and Chemical engineering,Shanghai Jiao Tong university,Shanghai 200240,China school of Materials Science and engineering Jiangsu University Zhenjiang China school of Chemistry and Chemical engineering Shanghai Jiao Tong University Shanghai China

This review introduces the kinetic theory of self-condensing vinyl polymerization (SCVP),including the SCVP of ab inimers,the SCVP with non-equal reactivity between A and B groups,the SCVP in the presence of a small amount of multifunctional initiators,also the SCVP of both inimers and *** analytical expressions of various molecular parameters for the resulting hyperbranched polymers,such as the molecular size distribution function,the average molecular weight,the polydispersity index and the degree of branching,are reviewed systematically.

关键词： kinetic theory self-condensing vinyl polymerization (SCVP) hyperbranched polymers

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effects of Al on Microstructure and High-Temperature Wear Properties of Austenitic Heat-Resistant Steel

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Journal of Iron and Steel Research International 2012年第3期19卷 62-66页

作者： ZHANG Yan1, SUN Yu-fu2, ZHAO Jing-yu2, GUAN Shao-kang2 (1. school of Materials engineering, Nanjing Institute of Technology, Nanjing 211167, Jiangsu, China 2. school of Materials Science and engineering, Zhengzhou university, Zhengzhou 450002, Henan, China) school of Materials engineering Nanjing Institute of Technology Nanjing Jiangsu China school of Materials Science and engineering Zhengzhou University Zhengzhou Henan China

Microstructure and high-temperature dry sliding wear at 600 ~C in ambient air of austenitic heat-resistant steel ZG40Cr25Ni20 with different contents （mass percent） of AI （0 to 7.10~） have been investigated. The results show that microstructures of 4.68% and 7.10% A1 addition content consist of the matrix and reinforcement of inter- metallic compound y＇ and carbide, while microstructures of ZG40Cr25Ni20 without A1 and with A1 of 1.68% are ab- sent of y＇. Higher wear resistance than the original ZG40Cr25Ni20 alloy is achieved in alloys with higher content of A1 under the same high-temperature wear test condition. The wear rates of Fe-25Cr-20Ni-7.10A1 and Fe-25Cr-20Ni- 4.68A1 are only 20.83% and 45.83% of that of Fe-25Cr-20Ni, respectively. Heat-resistant steels with higher con- tents of AI （4.72% and 7.10%） have higher hardness than those with lower contents of AI （1.68% and 0）. Wear mechanisms of ZG40Cr25Ni20 are considered as severe plough plastic deformation and slight adhesive. However, wear mechanisms of Fe-25Cr-20Ni 4.68A1 are light micro-cutting and oxidation-wear, while that of Fe-25Cr-20Ni- 7. 10A1 are severe adhesive transfer and oxidation-wear_

关键词： austenitic heat resistant steel Al microstructure high-temperature sliding wear mechanism

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Theoretical study of bifurcated bent blue-shifted hydrogen bonds CH_2…Y

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Science China Chemistry 2008年第7期51卷 623-631页

作者： LI AnYong school of Chemistry and Chemical engineering, Southwest university, Chongqing 400715, China school of Chemistry and Chemical engineering Southwest University Chongqing China

ab initio quantum chemistry methods were applied to study the bifurcated bent hydrogen bonds Y… H2CZ (Z = O, S, Se) and Y…H2CZ2 (Z = F, Cl, Br) (Y = Cl-, Br-) at the MP2/6-311++G(d,p) and MP2/6-311++G(2df,2p) levels. The results show that in each complex there are two equivalent blue-shifted H-bonds Y…H—C, and that the interaction energies and blue shifts are large, the energy of each Y…H—C H-bond is 15-27 kJ/mol, and Δr(CH) = -0.1 - -0.5 pm and Δv(CH) = 30 - 80 cm-1. The natural bond orbital analysis shows that these blue-shifted H-bonds are caused by three factors: large rehybridization; small direct intermolecular hyperconjugation and larger indirect intermolecular hy- perconjugation; large decrease of intramolecular hyperconjugation. The topological analysis of elec- tron density shows that in each complex there are three intermolecular critical points: there is one bond critical point between the acceptor atom Y and each hydrogen, and there is a ring critical point inside the tetragon YHCH, so these interactions are exactly H-bonding.

关键词： bifurcated bent H-bonds blue-shifted H-bonds topological property of electron density intramolecular hyperconjugation

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Minimal regular 2-graphs and applications

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Science China Mathematics 2006年第2期49卷 158-172页

作者： FAN Hongbing, LIU Guizhen & LIU Jiping Department of Physics and Computer Science, Wilfrid Laurier university, Waterloo, ON., N2L 3C5 Canada school of Mathematics and System Science, Shandong university, Jinan 250100, China Department of Mathematics and Computer Science, university of Lethbridge, Lethbridge, ab., T1K 3M4, Canada Department of Physics and Computer Science Wilfrid Laurier University Waterloo Canada school of Mathematics and System Science Shandong University Jinan China Department of Mathematics and Computer Science University of Lethbridge Lethbridge Canada

A 2-graph is a hypergraph with edge sizes of at most two. A regular 2-graph is said to be minimal if it does not contain a proper regular factor. Let f2(n) be the maximum value of degrees over all minimal regular 2-graphs of n vertices. In this paper, we provide a structure property of minimal regular 2-graphs, and consequently, prove that f2(n) = n+3-i/3, where 1 ≤ i ≤ 6, i ≡ n (mod 6) and n ≥ 7, which solves a conjecture posed by Fan, Liu, Wu and Wong. As applications in graph theory, we are able to characterize unfactorable regular graphs and provide the best possible factor existence theorem on degree conditions. Moreover, fa(n) and the minimal 2-graphs can be used in the universal switch box designs, which originally motivated this study.

关键词： graph regular factor 2-graph switch box design.

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Use of Farmers’ Indicators to evaluate the Sustainability of Cropping Systems on Sloping Land in Yunnan Province, China

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Pedosphere 2009年第3期19卷 344-355页

作者： M. SUBeDI T. J. HOCKING M. A. FULLeN A, R. McCReA e. MILNe WU Bo-Zhi D. Jo MITCHeLL school of Applied Sciences The University of Wolverhampton Wulfruna Street Wolverhampton WV1 1LY （UK） The Macaulay Institute Craigiebuekler Aberdeen AB15 8QH （UK） Yunnan Agricultural university Kunming 650201 （China）

Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers＇ response can be grouped into seven major aspects： i） effects on income, ii） effects on production resources, iii） effects on crop management, iv） existing local knowledge about the technology, v） availability of inputs, vi） access to information, and vii） socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers＇ awareness of ago-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes.

关键词： agro-environmental sustainability China farmers' evaluation farmers' indicator paired catchments

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