检索结果-南通市图书馆

The Effect of Body Pitching on Leg-Spring Behavior in Quadruped Running

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic engineering 2010年第3期7卷 219-227页

作者： Qi Deng, Shigang Wang, Qinghua Liang, Jinqiu Mo school of mechanical engineering, shanghai jiao tong university, shanghai 2.02.0 P. R. china [a] school of mechanical engineering Shanghai Jiao Tong University Shanghai 200240 P. R. China

In this paper we investigated how the running speed would affect the dynamics of body pitching, and whether body inertiais important for animals. Passive trotting of spring-mass model and passive bounding of spring-beam model were studied atdifferent speeds for different sets of body parameters respectively. Furthermore, different body inertias were used in *** found that running speed exerts effect on leg performance by means of centrifugal force. The centrifugal force can be understoodas an enhancement to the natural frequency of the spring-mass system. The disadvantage of body pitching may beoffset by the great increase in centrifugal force at high speed. The results also reveal that body mass distribution might not be themain reason for the difference in maximal running speeds of different animals.

关键词： body pitching leg performance running speed centrifugal force body inertia

Nonlinear analysis of slow drift extreme responses of a compliant offshore structure

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2009年第5期25卷 651-657页

作者： Yingguang Wang Jiahua Tan school of Naval Architecture, Ocean and Civil engineering,shanghai jiao tong university, 2.02.0 shanghai, china school of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University 200240 Shanghai China

This paper first demonstrates that the accuracy and efficiency of the method of numerical simulation often used is not very high in predicting the slow drift surge extreme responses of a compliant offshore structure. Next, the slow drift surge extreme responses of the structure are analyzed via the path integral solution racy and efficiency of the PIS （PIS） method, and the accumethod is found to be higher than those of the numerical simulation method. A compound PIS （CPIS） method is first proposed in this article to further improve the efficiency of the path integral solution method, and the accuracy and efficiency of the CPIS method is validated.

关键词： Compliant offshore simulation Path integral solution solution structure Numerical Compound path integral

Experimental Study on Turbulent Structure of Humid Air Flame in a Bluff-body Burner

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2009年第2期18卷 185-192页

作者： Bing Ge Shu-Sheng Zang Pei-qing Guo school of mechanical engineering, shanghai jiao tong university, shanghai 2.02.0, china 800, Dong Chuan Road, shanghai, china. Zip: 2.02.0 school of mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China 800 Dong Chuan Road Shanghai China Zip: 200240

The main objective of the present experimental study is to analyze the turbulent structure in humid airnon-premixed flame, and determine the effect of humidity on the flow field and the flame stability limit in turbulentnon-premixed flame. Particle Image Velocimetry (PIV) is used to capture the instantaneous appearance ofvortex structures and obtain the quantitative velocity field. The distributions of Reynolds shear stress, mean androot-mean squared fluctuating (rms) velocities are examined to get insight into the effect of fuel-to-air velocity ratioon velocity flow field. The results show that with steam addition, the air-driven vortex in the bluff-body wakeis thinner; the biggest peaks of rms velocity and Reynolds shear stress are lower; the distance between the peaksof rms velocity on the sides of centerline reduces. Besides these, the flame stability is affected. Both central fuelpenetration limit and partially quenching limit reduce with steam addition.

关键词： humid air combustion turbulence measurement PIV

WATER ENTRY OF A WEDGE BASED ON SPH MODEL WITH AN IMPROVED BOUNDARY TREATMENT

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 750-757页

作者： GONG Kai LIU Hua WANG Ben-long Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200240 China

The hydrodynamic problem of a two-dimensional wedge entering water is studied based on Smoothed Particle Hydrodynamics （SPH） model. A non-reflection boundary treatment for SPH method is proposed to reduce the reflection of sound waves. The boundary pressure is obtained using an improved coupling boundary treatment approach, which is validated by comparing the simulation results with experimental and analytical results in literature. A series of cases with different initial entering velocities are simulated. The maximum force on the wedge and the corresponding time required to reach it for the different cases of initial entering velocities of the wedge are obained and fitted into formulas against the initial entering velocity of the wedge. The maximum drag coefficients of the wedge for the different cases with Froude number greater than 2 are all near the value of 0.91.

关键词： water entry Smoothed Particle Hydrodynamics (SPH) non-reflection boundary

CALCULATION OF ADDED MASS OF A VEHICLE RUNNING WITH CAVITY

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第3期22卷 312-318页

作者： LI Jie LU Chuan-jing HUANG Xuan Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

A numerical method is developed to obtain the added mass coefficients of a vehicle running with cavity in numerical simulation for the multiphase flow of the vehicle which is imposed an added vibration and analyzing its hydrodynamic loads. The method is verified through the cases of non-cavitating sphere and ellipsoid. The changing rule of the added mass of a sphere during water exit is gained. Then the influence of cavitation on the added mass of a cylinder is studied. The results show that λ 11, λ22, λ26, λ66 all decrease as the cavitation number reduces and the length of the attached cavity increases. There is almost a linear relationship between the cavity length and λ22 .The base cavity has great influence on λ11 its contribution decreases more than 60%, when the cavitation number changes from 0.6 to 0.2.

关键词： added mass cavity carrying forced vibration method

Data fusion for target tracking in wireless sensor networks using quantized innovations and Kalman filtering

在线全文

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2012年第3期55卷 530-544页

作者： XU Jian1,2 , LI JianXun1,2 & XU Sheng3 1Department of Automation, Science and Technology on Avionics Integration Laboratory, shanghai jiao tong university, shanghai 2.02.0, china 2Department of Automation, System Control and Information Processing, Ministry of Education of china, shanghai jiao tong university, shanghai 2.02.0, china 3school of mechanical engineering, shanghai jiao tong university, shanghai 2.02.0, china 1. Department of Automation Science and Technology on Avionics Integration Laboratory Shanghai Jiao Tong University Shanghai 200240 China2. Department of Automation System Control and Information Processing Ministry of Education of China Shanghai Jiao Tong University Shanghai 200240 China3. School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China

A novel networked data-fusion method is developed for the target tracking in wireless sensor networks (WSNs). Specifically, this paper investigates data fusion scheme under the communication constraint between the fusion center and each sensor. Such a message constraint is motivated by the bandwidth limitation of the communication links, fusion center, and by the limited power budget of local sensors. In the proposed scheme, each sensor collects one noise-corrupted sample, performs a quantizing operation, and transmits quantized message to the fusion center. Then the fusion center combines the received quantized messages to produce a final estimate. The novel data-fusion method is based on the quantized measurement innovations and decentralized Kalman filtering (DKF) with feedback. For the proposed algorithm, the performance analysis of the estimation precision is provided. Finally, Monte Carlo simulations show the effectiveness of the proposed scheme.

关键词： data fusion target tracking limited bandwidth quantized innovation Kalman filtering

Metal chlorides loaded on activated carbon to capture elemental mercury

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2010年第11期22卷 1814-1819页

作者： Zhemin Shen,Jing Ma,Zhijian Mei,Jianda Zhang school of Environmental Science and engineering,shanghai jiao tong university,shanghai 2.02.0,china [a] school of Environmental Science engineering Shanghai Jiao Tong University Shanghai 200240 China

Activated carbon （AC） was considered to be an effective sorbent to control mercury in combustion systems. However, its capture capacity was low and it required a high carbon-to-mercury mass ratio. AC loaded with catalyst showed a high elemental mercury （Hg 0 ） capture capacity due to large surface area of AC and high oxidization ability of catalyst. In this study, several metal chlorides and metal oxides were used to promote the sorption capacity of AC. As a result, metal chlorides were better than metal oxides loaded on AC to remove gaseous mercury. X-ray diffractometer （XRD）, thermogravimetric analyzer （TGA） and specific surface area by Brunauer- Emmett-Teller method （BET） analysis showed the main mechanisms： first, AC had an enormous surface area for loading enough MClx; second, Cl and MxOy were generated during pyrogenation of MClx; finally, there were lots of active elements such as Cl and MxOy which could react with elemental mercury and convert it to mercury oxide and mercury chloride. The HgO and HgCl 2 might be released from AC’s porous structure by thermo regeneration. A catalytic chemisorption mechanism predominates the sorption process of elemental mercury. As Co and Mn were valence variable metal elements, their catalytic effect on Hg 0 oxidization may accelerate both oxidation and halogenation of Hg 0 . The sorbents loaded with metal chlorides possessed a synergistic function of catalytic effect of valence variable metal and chlorine oxidation.

关键词： mercury activated carbon flue gas metal chloride metal oxide

NEAR WAKE OF A MODEL HORIZONTAL-AXIS WIND TURBINE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第2期21卷 285-291页

作者： HU Dan-mei DU Zhao-hui school of Power and Enviromental engineering Shanghai University of Electric Power Shanghai 200090 China school of mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China

An experimental investigation on the properties of the near wake behind the rotor of a Horizontal-Axis Wind Turbine （HAWT） was carried out at model scale. Measurements were made with a stationary slanted hot-wire anemometer using the technique of phase-locked averaging. The primary aim is to study the formation and development of the three-dimensional wake. Five axial locations were chosen within four chord lengths of the blades over a range of tip speed ratios. The results show that during the downstream developmerit of the wake, the wake centre traces a helical curve with its rotation direction opposite to that of the rotor. The distribution of mean velocity behind the HAWT rotor reveals an expansion and a decay of the three-dimensional wake. The shapes of the mean velocity distribution are similar along the blades span at the same downstream axial location. It is shown that the turbulence levels in the wake are higher than those in the non-wake region. The circumferential component and the radial component of the turbulence intensity are higher than the axial component. Our study offers some food of thought for better understanding of the physical features of the flow field as well as the performance of HAWT.

关键词： horizontal-axis wind turbine wake flow hot-wire anemometry experimental

SIMULATION OF BLOOD FLOW IN INTRACRANIAL ICA-PCOMA ANEURYSM VIA COMPUTATIONAL FLUID DYMAMICS MODELING

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第5期21卷 583-590页

作者： WANG Qing WANG Wei-zhe FEI Zhi-min LIU Ying-zheng CAO Zhao-min school of mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China Renji Hospital Shanghai Jiao Tong University Shanghai 200001 China

In the present study, hemodynamics of the internal carotid artery-posterior communicating artery （ICA-PComA） was numerically modeled with CFD approach. The steady and pulsating blood flow in the ICA-PComA was simulated. The main concern was placed on the influence of aneurysm geometry on the local hemodynamics by changing the sac diameter and Aspect Ratio （AR） of the aneurysm. The numerical results show the significantly weakened Wall Shear Stress （WSS） and the intensified wall pressure in the aneurysm as AR is increased. Two factors, i.e., low WSS and high pressure of the aneurysm, may play important roles in the fragile change of the aneurysm and the final rupture. The distributions of Time-Averaged WSS （TAWSS）, Oscillatory Shear Index （OSI） and spatial WSS Gradients （WSSG）） were determined and discussed in view of their influences on the evolution of ICA-PComA aneurysm.

关键词： CFD intracranial aneurysm hemodynamics