检索结果-南通市图书馆

HYDRAULIC CHARACTERISTICS OF PLUG ENERGY DISSIPATER IN FLOOD DISCHARGE TUNNEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第6期21卷 799-806页

作者： TIAN Zhong xu Wei-lin wang Wei LIU shan-jun State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China

The hydraulic characteristics of three types of plugs, namely, the single plug, the stepped plug and the gradually contracted plug were studied by means of experimental and numerical simulations. Main research findings are as follows. For the single plug, the pressure recovery lengths inside and after the plug range from 0.63-1.05 times and 2.02-2.84 times of the tunnel diameter, respectively. For the stepped plug, the lengths are 0.24-0.32 times and 1.62-2.84 times of the tunnel diameter, respectively. The best ratio of the inlet diameter to the outlet diameter of the gradually contracted plug can be expressed by a linear function. The relationship between the head loss coefficient and the area contraction ratio is obtained. The incipient cavitation numbers of different plugs are experimentally and numerically determined, and the incipient cavitation numbers are expressed by a formula. Model experiment with scale of 1：50 was carried out on a pressure tunnel with three-stage gradually contracted plugs. The results show that this type of energy dissipater is suitable for spill tunnels of high head （nearly 200 m） and large flow rate （nearly 2500 m^3/s）.

关键词： plug incipient cavitation number energy dissipater CFD

Coherence Rotation in the Reaction ^(19)F+ ^(51)V

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1996年第10期13卷 727-729页

作者： wang Qi LU jun xu Hu-shan LI Song-lin ZHU Yong-tai ZHANG Yu-hu LI Zhi-chang Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000 China Institute of Atomic Energy Beijing 102413

Excitation functions of the dissipative products in the reaction 19F+51V have been measured from 102.25 to 109.50MeV by 250keV steps at θl = 21.7°, 36.1°and 40.5°. The rotation angular velocities ω and the energy coherence widths of the corresponding dinuclear systems were extracted. The coherence rotation and its importance in the reaction process have been discussed.

关键词： rotation steps 19F

AERATION EFFECT OF SUBMERGED JET ON HYDRAULIC CHARACTERISTICS

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 Hydrodynamics 2002年第3期14卷 35-39页

作者： Liu, shan-jun xu, Wei-lin wang, Wei Qu, Jing-xue Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China

A water-air two-phase turbulence mathematical model was proposed, The mass-weighted average was adopted for velocity, air mass fraction and turbulent parameters. The algebraic stress equation was used to calculate the Reynolds stress. The pulsating flux of air mass fraction was simulated by employing the concept of the eddy viscosity. The numerical simulation of aerated flow in plunge pool shows that, for the same depth, aeration may decrease the time-averaged pressure on pool floor and increase slightly the turbulent intensity. The computed concentration and pressure distributions coincide with the experimental data.

关键词： Computer simulation Mathematical models Pressure distribution Turbulent flow Two phase flow

NUMERICAL SIMULATION OF 3-D FLOW FIELD IN ARCIFORM PLUNGE POOL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第3期14卷 106-110页

作者： xu, Wei-lin Liu, shan-jun wang, Wei Qu, Jing-xue Diao, Ming-jun Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China

The 3-D complex turbulent flow fields in a plunge pool with arciform bottom are simulated by using the k-Ε model in body-fitted coordinates. The calculated results reveal the flow characteristics in the arciform plunge pool under the different flood discharge conditions, which can not be easily obtained in the physical model test because the measurement of the complex velocity is very difficult. The calculated flow fields are helpful to understand the hydraulic characteristics of plunge pool deeply. The calculated and the measured pressure distributions on the pool bottom are compared and in good agreement.

关键词： Computer simulation Flood control Flow of fluids Pressure distribution Three dimensional

Levels of Germinable Seed in Topsoil and Yak Dung on an Alpine Meadow on the North-East Qinghai-Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2013年第12期12卷 2243-2249页

作者： YU Xiao-jun xu chang-lin wang Fang shanG Zhan-huan LONG Rui-jun College of Grassland Science Gansu Agricultural University/Key Laboratory of Grassland EcosystemMinistry of Education/Sino-U.S.Center for Grassland Ecosystem Sustainability College of Agronomy Gansu Agricultural University International Centre for Tibetan Plateau Ecosystem Management Lanzhou University

In order to clarify the interactive mechanism between grazing yak and alpine meadow on the Qinghai-Tibetan Plateau,our study assessed seed density（by species） in the topsoil of alpine meadow with different grazing intensities in the Tianzhu area,north-eastern margins of the Qinghai-Tibetan Plateau and their rates of occurrence in yak *** density in the topsoil of the lightly grazed,moderately grazed,heavily grazed and extremely grazed alpine meadows in November,2010 were 1 551,1 692,2 660 and 1 830 grains m-2,while in the same meadows in April,2011 densities were 1 530,2 404,2 530 and 2 692 grains m-2,*** the cold season pasture,mean seed density in yak dung from November to April in the lightly grazed,moderately grazed,heavily grazed and extremely grazed sites were 121,127,187,and 120 grains kg-1of dry yak *** proportion of total seed numbers in yak dung to soil seed bank in lightly grazed,moderately grazed,heavily grazed and extremely grazed alpine meadow was 1.40,2.62,0.69,and 0.90%.12 species out of the 47 were not found in topsoil but were found in yak dung,10 species out of 45 were not found in yak dung but were found in the *** dispersal by yaks is therefore very important for soil seed bank and plant biodiversity and population dynamics in alpine meadows.

关键词： alpine meadow seeds endozoochory seed density soil seed bank yak dung

Quantification and analysis of anthocyanin and flavonoids compositions,and antioxidant activities in onions with three different colors

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2016年第9期15卷 2175-2181页

作者： ZHANG Shi-lin DENG Peng xu Yu-chao Lü shan-wu wang Jian-jun State Key Laboratory of Crop Genetics and Germplasm Enhancement Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China Ministry of Agriculture/College of Horticulture Nanjing Agricultural University

Onion（Allium cepa L.） is a very important vegetable crop widely cultivated throughout the world. In this study, we measured total anthocyanins and flavonols of onions of three colors. The fresh weight（FW） of total anthocyanins were（29.99±1.19）,（9.64±1.30） and（0.75±0.40） mg 100 g^–1 fruit in red, yellow and white onions, respectively. Likewise, the FW of total flavonoids were（111.10±5.98）,（36.64±3.59）, and 0 mg 100 g^–1 in red, yellow and white, respectively. Four types of anthocyanins（delphinidin 3,5-diglycosides, cyanidin 3,5-diglycosides, cyanidin 3-glycosides and cyanidin 3-（6′′-malonyl）-glucopyranoside） and two kinds of flavonoids（quercetin and quercetin 3-glycosides） were identified in two varieties（red and yellow bulb） of onions by HPLC/DAD-ESI/MS. The total polyphenol contents were also measured by means of Folin-Ciocalteu method. Moreover, all the concentrations of anthocyanins, flavonoids and polyphenols showed significantly positive correlations with antioxidant activities measured by DPPH˙, ABTS˙＋ and FRAP assays. This study provided information on anthocyanin and flavonoids compositions that will be useful for onion breeding.

关键词： onion(Allium cepa L.) anthocyanins flavonoids antioxidant activity HPLC-DAD-ESI/MS

THEORETICAL AND EXPERIMENTAL STUDIES OF HYDRAULIC CHARACTERISTICS OF DISCHARGE TUNNEL WITH VORTEX DROP

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第4期22卷 582-589页

作者： CHEN Hua-yong xu Wei-lin DENG jun NIU Zhi-pan LIU shan-jun wang Wei State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan University Chengdu 610065 China

The velocities at given points in the volute chamber,the contracted section and the vertical dropshaft of a discharge tunnel with vortex drop were measured by a small specially designed L-shaped tube,as Laser Doppler Velocimetry（LDV） or Particle Image Velocimetry（PIV） would not work there due to the special structure of the discharge tunnel with vortex *** empirical formulas were proposed to predict the velocities and the angles of the velocities made with the vertical direction θ.The theoretical analysis results were in good agreement with experimental ***,the method proposed in this paper can be used to analyze related characteristics of discharge tunnels with vortex ***,different model scales were considered to predict the cavitation characteristics on the wall of a dropshaft in practical engineering.

关键词： discharge tunnel with vortex drop dropshaft velocity wall pressure cavitation

EXPERIMENTAL INVESTIGATION OF EMERGENCY GATE SHUTTING FOR ORIFICE TUNNEL

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第3期14卷 29-34页

作者： wang, Wei Yang, Yong-Quan xu, Wen-lin Liu, shan-jun Diao, Ming-jun Zhang, Jian-Min Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China

In the process of the emergence gate shutting of one orifice tunnel, a big noise and great vibration may be observed in the mid gate chamber. In order to guarantee the working safety of orifice tunnels, an experimental investigation is carried out in Sichuan University. In the investigation, the fluctuation pressure along the tunnel and the wind velocity in the entry of emergency gate are measured. In the mean time, the fluid state in orifice tunnel is carefully observed and analyzed. The reasons of the noise and vibration in the mid gate chamber are found out and some countermeasures are presented in this paper. The conclusions are useful to the orifice tunnels with high water head and huge discharge.

关键词： Pressure measurement Tunnels Velocity Vibrations (mechanical) Wind

NUMERICAL SIMULATION OF TURBULENT FLOW THROUGH THROAT-TYPE ENERGY-DISSIPATORS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第3期14卷 135-138页

作者： Dong, Jian-Wei xu, Wei-lin Deng, jun Liu, shan-jun wang, Wei Qu, Jing-xue Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China

The flow through the throat-type energy-dissipators is calculated by using an axis-symmetrical K-Ε turbulence model. The velocity field, the pressure field and the distributions of turbulent energy and its dissipation rate are acquired. The energy dissipation through the throat-type energy-dissipators can be seen in detail. The calculated pressure distribution is compared with the measured and is in good agreement. The results are useful to understand deeply the flow characteristics of the throat-type energy-dissipators.

关键词： Computer simulation Flow of fluids Pressure distribution Turbulent flow Velocity