检索结果-南通市图书馆

One Novel Hydraulic Actuating System for the Lower-Body Exoskeleton

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2021年第1期34卷 20-29页

作者： Maowen Sun Xiaoping Ouyang Jouni Mattila Huayong Yang Gang Hou State Key Laboratory of Fluid Power&Mechatronic Systems Zhejiang UniversityHangzhou 310027China department of Intelligent hydraulics and Automation Tampere University33101 TampereFinland Guiyang HYC Hydraulic Co. LtdGuiyang 550018China

The hydraulic exoskeleton is one research hotspot in the field of robotics,which can take heavy load due to the high power density of the hydraulic ***,the traditional hydraulic system is normally centralized,inefficient,and bulky during application,which limits its development in the *** improving the robot's performance,its hydraulic actuating system should be optimized *** this paper a novel hydraulic actuating system(HAS)based on electric-hydrostatic actuator is proposed,which is applied to hip and knee *** HAS integrates an electric servo motor,a high-speed micro pump,a specific tank,and other components into a *** specific parameters are obtained through relevant simulation according to human motion data and load *** dynamic models of the HAS are built,and validated by the system *** of trajectory tracking and human-exoskeleton interaction are carried out,which demonstrate the proposed HAS has the ability to be applied to the *** with the previous prototype,the total weight of the HAS in the robot is reduced by about 40%,and the power density is increased by almost 1.6 times.

关键词： Hydraulic actuating system(HAS) Lower-body exoskeletons Lightweight and integrated System identification Working mode test

Particle support mechanism in viscous debris flows at Jiangjia Ravine,Yunnan,China

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 1999年第5期42卷 550-555页

作者：王裕宜费祥俊 Chengdu Institute of Mountain Disasters and Environment Chinese Academy of Sciences Dongchuan Debris Flow Observation and Research Station Chinese Academy of Sciences Chengdu 610041 China department of hydraulics Tsinghua University

Hyperconcentrated viscous debris flows can move rapidly on low-gradient ravine under shear, because they have highly excessive pore pressure. The relationship between excessive pore-pressure (P e ) and volume concentration (C vt ) in viscous debris flows, i. e.P e =2 494. 76C vt 0.94, is quantitatively shown; the correlation coefficienty=0.967 1, 95% confidence interval is 0.905 3.ρ3.7. About 92.29% of all grains (by weight) is supported by excessive pore pressure.

关键词： debris flow particle support excessive pore-pressure.

Debris Flow Hazard Assessment Using Set Pair Analysis Models:Take Beichuan County as an Example

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2014年第4期11卷 1015-1022页

作者： YANG Feng-guang LIANG Yue SINGH Vijay P. WANG Wen-sheng ZHOU Xiao-quan LIU Xing-nian CAO Shu-you HUANG Er WU Yan-hua State Key Laboratory of hydraulics and Mountain River Engineering Sichuan University College of Water Resource & Hydropower Sichuan University department of Biological and Agricultural Engineering Texas A & M University College Station Texas 77843-2117 USA

Assessment of debris flow hazards is important for developing measures to mitigate the loss of life and property and to minimize environmental damage. Two modified uncertainty models, Set Pair Analysis （SPA） and modified Set Pair Analysis （mSPA）, were suggested to assess the regional debris flow hazard. A ease study was conducted in seven towns of the Beichuan county, Sichuan Province, China, to test and compare the application of these two models in debris flow hazard assessment. The results showed that mSPA only can fit for value-variables, but not for non value-variable assessment indexes, Furthermore, as for a given assessment index xi, mSPA only considers two cases, namely, when grade value increases with xi and when grade value decreases with xi. Thus, mSPA can not be used for debris flow hazard assessment but SPA is credible for the assessment because there are no limitations when using SPA model to assess the debris flow hazard. Therefore, in this study SPA is proposed for assessing debris flow hazard.

关键词： Set Pair Analysis (SPA) Modified SetPair Analysis (mSPA) Debris flow Hazardassessment Connection degree

A novel mesh-free poly-cell Galerkin method

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第4期25卷 517-527页

作者： C. Zheng X. H. Tang J. H. Zhang S. C. Wu State Key Laboratory of hydraulics and Mountain River Engineering Sichuan University State Key Laboratory of Digital Manufacturing and Equipment Technology Huazhong University of Science and Technology Centre for Advanced Computations in Engineering Science (ACES) Department of Mechanical EngineeringNational University of Singapore

A novel numerical method is explored and named as mesh-free poly-cell Galerkin method. An improved moving least-square （MLS） scheme is presented, which can avoid the matrix inversion in standard MLS and can be used to construct shape functions possessing delta Kronecher property. A new type of local support is introduced to ensure the alignment of integral domains with the cells of the back-ground mesh, which will reduce the difficult in integration. An intensive numerical study is conducted to test the accuracy of the present method. It is observed that solutions with good accuracy can be obtained with the present method.

关键词： MPG CO-MSL Mesh-free Meshless Voronoi diagram

Temporal evolution of scour at bridge abutments in compound channels

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2022年第5期37卷 662-674页

作者： Yifan Yang Bruce W.Melville Xiaozhou Xiong Lu Wang School of Engineering The University of Waikato Risland New Zealand department of Civil and Environmental Engineering The University of Auckland State Key Laboratory of hydraulics and Mountain River Engineering College of Water Resource and Hydropower Sichuan University

Bridge abutment-induced sediment scour in compound river channels is time-sensitive during floods, and, thus, estimating the scour rate has significance in design. In the current study, large-scale laboratory experiments were done to examine the influence of multiple factors on scour evolution,including channel geometry, bed mobility(clear-water or live-bed), and lateral(embankment intrusion) and vertical(deck submergence) flow contractions. A new method is applied for scour measurement and determination of characteristic scour trends. Results show that the nondimensional time scale is related to flow intensity and may peak before reaching the clear-water scour threshold; the corresponding equations also are derived. It is found that the use of scour countermeasures has a significant impact on the scour rate, and the existing equations for unprotected abutments have limitations. Under clear-water conditions, the scour rate is closely related to the overall flow contraction, which can be better reflected by the ratio of the approaching unit discharge to that at the bridge section. Specifically, the effect of vertical flow contraction on scour rate is more dominant than other factors. Two scour rate curves are derived to suit different structural and flow contraction types for clear-water scour. In contrast, the live-bed scour rate data are generally consistent and fall in a narrow band, showing less dependence on other factors. Finally, a new design approach is established to estimate the time scale and scour rate using the new equations proposed in this paper.

关键词： Abutment scour Temporal evolution Compound channel Time scale Scour rate

A RANS-VoF Numerical Model to Analyze the Output Power of An OWC-WEC Equipped with Wells and Impulse Turbines in A Hypothetical Sea-State

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第6期34卷 760-771页

作者： Paulo R.F.Teixeira Rafael A.A.C.Gonçalves Eric Didier Engineering School Universidade Federal do Rio Grande-FURGRio GrandeRS 96203-900Brazil Harbours and Maritime Structures Division Hydraulics and Environment DepartmentLaboratório Nacional de Engenharia Civil-LNECLisbon 1700-066Portugal

Wave energy is a renewable source with significant amount in relation to the global demand. A good concept of a device applied to extract this type of energy is the onshore oscillating water column wave energy converter(OWC-WEC). This study shows a numerical analysis of the diameter determination of two types of turbines, Wells and Impulse, installed in an onshore OWC device subjected to a hypothetical sea state. Commercial software FLUENT?,which is based on RANS-VoF(Reynolds-Averaged Navier-Stokes equations and Volume of Fluid technique), is employed. A methodology that imposes air pressure on the chamber, considering the air compressibility effect, is used. The mathematical domain consists of a 10 m deep flume with a 10 m long and 10 m wide OWC chamber at its end(geometry is similar to that of the Pico's plant installed in Azores islands, Portugal). On the top of the chamber, a turbine works with air exhalation and inhalation induced by the water free surface which oscillates due to the incident wave. The hypothetical sea state, represented by a group of regular waves with periods from 6 to 12 s and heights from 1.00 to 2.00 m(each wave with an occurrence frequency), is considered to show the potential of the presented methodology. Maximum efficiency(relation between the average output and incident wave powers) of46% was obtained by using a Wells turbine with the diameter of 2.25 m, whereas the efficiency was 44% by an Impulse turbine with the diameter of 1.70 m.

关键词： wave energy oscillating water column Wells turbine Impulse turbine RANS-VoF compressible air

On study of non-spherical bubble collapse near a rigid boundary

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2020年第3期32卷 523-535页

作者： Xiao-jian Ma Xin Zhao Biao Huang Xiao-ying Fu Guo-yu Wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China department of Mechanics School of Aerospace EngineeringBeijing Institute of TechnologyBeijing100081China State Key Laboratory of hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

This paper applies numerical methods to investigate the non-spherical bubble collapse near a rigid boundary. A three-dimensional model, with the mass conservation equation reformulated for considering the compressibility effect, is built to deal with the coupling between the pressure and the flow velocity in the momentum and energy equations and to simulate the temporal evolution of the single bubble oscillation and its surrounding flow structure. The investigations focus on the global bubble patterns and its schlieren contours, as well as the high-speed jet accompanied when the bubble collapses and the counter jet is generated in the rebound stage. The results show that the robust pressure waves emitted due to the bubble collapse lead to substantial changes of the flow structures around the bubble, especially the formation of the counter jet generated in the rebound stage. Furthermore, compared with the high-speed jet when the bubble collapses, the counter jet in the rebound stage emits the momentum several times greater in the magnitude and in diametrically opposite direction at the monitoring point.

关键词： Bubble jet rigid boundary numerical simulation volume of fluid(VOF) pressure wave

Waste oyster shell as a kind of active filler to treat the combined wastewater at an estuary

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2013年第10期25卷 2047-2055页

作者： Hongbing Luo Gu Huang Xiaoying Fu Xiaoling Liu Daocai Zheng Jian Peng Ke Zhang Bo Huang Liangqian Fan Fenghui Chen Xiubo Sun College of Urban and Rural Construction Sichuan Agricultural University China Northwest Municipal Engineering Design Research Institute Co. Ltd. State Key Laboratory of hydraulics and Mountain River Engineering Sichuan University department of Civil and Geological Engineering University of Saskatchewan

Estuaries have been described as one of the most difficult environments on Earth. It is difficult to know how to treat the combined wastewater in tidal rivers at the estuary, where the situation is very different from ordinary fresh water rivers. Waste oyster shell was used as the active filler in this study in a bio-contact oxidation tank to treat the combined wastewater at the Fengtang Tidal River. With a middle-experimental scale of 3.0 ma/day, the average removal efficiency of COD, BOD, NH3.N, TP and TSS was 80.05%, 85.02%, 86.59%, 50.58% and 85.3.%, respectively, in this bio-contact oxidation process. The living microbes in the biofilms on the waste oyster shell in this bio-contact oxidation tank, which were mainly composed of zoogloea, protozoa and micro-metazoa species, revealed that waste oyster shell as the filler was suitable material for combined wastewater degradation. This treatment method using waste oyster shell as active filler was then applied in a mangrove demonstration area for water quality improvement near the experiment area, with a treatment volume of 5 × 10^3.m^3.day. Another project was also successfully applied in a constructed wetland, with a wastewater treatment volume of 1 ×10^3.m^3.day. This technology is therefore feasible and can easily be applied on a larger scale,

关键词： waste oyster shell active filler combined wastewater treatment tidal estuary engineering application

Estimation and inter-comparison of infiltration models in the agricultural area of the Mitidja Plain, Algeria

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2023年第12期15卷 1474-1489页

作者： Amina MAZIGHI Hind MEDDI Mohamed MEDDI Ishak ABDI Giovanni RAVAZZANI Mouna FEKI Higher National School of hydraulics of Blida Blida 09000Algeria department of Civil Engineering and hydraulics University of JijelJijel 18000Algeria department of Civil and Environmental Engineering Polytechnic University of MilanMilan 20133Italy

Infiltration is an important part of the hydrological cycle, and it is one of the main abstractions accounted for in the rainfall-runoff modeling. The main purpose of this study is to compare the infiltration models that were used to assess the infiltration rate of the Mitidja Plain in Algeria. Field infiltration tests were conducted at 40 different sites using a double ring infiltrometer. Five statistical comparison criteria including root mean squared error(RMSE), normalized root mean squared error(NRMSE), coefficient of correlation(CC), Nash-Sutcliffe efficiency(NSE), and Kling-Gupta efficiency(KGE) were used to determine the best performing infiltration model and to confirm anomalies between predicted and observed values. Then we evaluated performance of five models(i.e., the Philip model, Kostiakov model, Modified Kostiakov model, Novel model, and Horton model) in simulating the infiltration process based on the adjusted performance parameters cited above. Results indicated that the Novel model had the best simulated water infiltration process in the Mitidja Plain in Algeria. However, the Philip model was the weakest to simulate the infiltration process. The conclusion of this study can be useful for estimating infiltration rate at various sites using a Novel model when measured infiltration data are not available and are useful for planning and managing water resources in the study area.

关键词： infiltration rate infiltration model double ring infiltrometer Mitidja Plain Novel model