检索结果-南通市图书馆

Science china(Technological Sciences) 2010年第8期53卷 2122-2128页

作者： ZHANG Yun &LI BenWei department of Airborne vehicle engineering,Naval Aeronautical engineering Institute,Yantai 264001,china department of Airborne vehicle engineering Naval Aeronautical Engineering Institute

A new noise reduction method for nonlinear signal based on maximum variance unfolding(MVU)is *** noisy sig- nal is firstly embedded into a high-dimensional phase space based on phase space reconstruction theory,and then the manifold learning algorithm MVU is used to p.r.orm nonlinear dimensionality reduction on the data of phase space in order to sep.r.te low-dimensional manifold representing the attractor from noise ***,the noise-reduced signal is obtained through reconstructing the low-dimensional *** simulation results of Lorenz system show that the proposed MVU-based noise reduction method outp.r.orms the KpCA-based method and has the advantages of simple p.r.meter estimation and low p.r.meter *** proposed method is applied to fault detection of a vibration signal from rotor-stator of aero engine with slight rubbing *** denoised results show that the slight rubbing features overwhelmed by noise can be effectively extracted by the proposed noise reduction method.

关键词： nonlinear noise reduction manifold learning maximum variance unfolding fault diagnosis

EVALUATION　OF　HFAM　ON　A　FLOW　OVEr　A　BACKWArD－FACING　STEp

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1996年第3期8卷 25-30页

作者： Zhang Xiao-yuan Li Wei (department of river engineering, Wuhan University of Hydraulic & Electric power engineering, Wuhan, 430072,, p. r. china) Wuhan Univ of Hydraulic & Electric Power Engineering Wuhan China

A numerical solution for steady incompressible fluid flow over a two-dimensional backward-facing step for laminar condition was developed using a Hybrid Finite Analysis Method (HFAM). Attention is focused on obtaining accurate solution. The result of HFAM on the above problem is comp.r.d with other numerical solutions and exp.r.mental data to evaluate its numerical accuracy. It is concluded that some of the serious discrepancies that have occurred between prediction and observation at a large reynolds number condition, and attributed in earlier studies to the inadequacy of two-dimensional model, had been due to the inaccuracy of the solution.

关键词： hybrid finite analysis method Navier-stokes laminar flow backwardfacing step.

Impact chaos control and stress release——A key for development of ultra fine vibration milling

在线全文

学校读者我要写书评

暂无评论

progress in Natural Science:Materials International 2002年第5期12卷 18-23页

作者： WANG Shulin(department of power engineering, University of Shanghai for Science and Technology, Shanghai 200093, china) Shanghai Univ Sci & Technol Dept Power Engn Shanghai 200093 Peoples R China

Through our previous exp.r.mental and analytical studies, it has been discovered that the key for the development of vibration milling is the impact chaos control and stress release. The necessities for the chaos control and stress release are: (i) to strictly e-liminate the sub-harmonics; (ii) to control the sup.r.harmonics to a lower level and (iii) to load the system compressively with relatively higher p.r.od, in order that the vibration energy can be absorbed by the p.r.icles effectively and sufficiently. A new vibration model for ultra fine milling is proposed, which has wide applications in prep.r.ng ultra fine p.r.icles.

关键词： vibration mills ultra fine milling impact chaos control stress release.

CO_2 Mitigation in Coal Gasification Cogeneration Systems with Integration of the Shift reaction, CO_2 Absorption and Methanol production

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 Thermal Science 2004年第3期13卷 193-198页

作者： Yuanyuan DUAN Jin ZHANG Key Laboratory of Thermal Science and power engineering, department of Thermal engineering, Tsinghua University, Beijing 100084, china Key Laboratory of Thermal Science and power engineering Department of Thermal Engineering Tsinghua University Beijing China

Cogeneration of electricity and liquid fuel can achieve higher efficiencies than electricity generation alone in Integrated Gasification Combined Cycle (IGCC), and cogeneration systems are also expected to mitigate CO2 emissions. A proposed methanol-electricity cogeneration system was analyzed in this pap.r.using exergy method to evaluate the specified system. A simple cogeneration scheme and a complicated scheme including the shift reaction and CO2 removal were comp.r.d. The results show that the complicated scheme consumes more energy, but has a higher methanol synthesis ratio with p.r.ial capture of *** those methanol and electricity cogeneration systems, the CO2 mitigation is not merely an additional process that consumes energy and reduces the overall efficiency, but is integrated into the methanol production.

关键词： cogeneration system methanol synthesis CO2 mitigation exergy analysis

THE FrICTIONAL rESISTANCE CHArACTErISTICS OF GAS LIQUID TWO pHASE FLOW IN HELICAL COILED TUBES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2000年第4期12卷 16-19页

作者： Zhou Yun long, Shi Hui xian department of Thermal power, Northeast china Institute of Electric power engineering, Jilin 132012, p.r.china (received Oct. 28, 1999) Dep. of Thermal power Northeast Inst. of Power Eng. Jilin 132012 China

This pap.r.deal with the frictional resistance characteristics of gas liquid two phase flow in vertical upward helical coiled tubes under the system pressure 0.1 0.6Mpa. By means of dimension analysis and π theorem, the correlation formulas were obtained for calculating the frictional resistance coefficients of gas liquid two phase flow in helical coiled tubes. The calculated results agree well with the exp.r.mental results.

关键词： frictional resistance gas liquid two phase flow helical coiled tubed

LINEAr ACTIVE STrUCTUrES AND MODES (Ⅱ) —DISCrETE SYSTEMS AND BEAMS

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2004年第8期25卷 854-862页

作者：王永刚龚靖School of Civil engineering and Mechanics Xi'an Jiaotong University Xi'an 710049 p.r.china department of Civil engineering Northeast china Institute of Electric power Jilin 132012 p.r.china 张景绘School of Civil engineering and Mechanics Xi'an Jiaotong University Xi'an 710049 p.r.china School of Civil engineering and Mechanics Xi'an Jiaotong University Xi'an 710049 P.R.ChinaSchool of Science Chang'an University Xi'an 710064 P.R.China

The basic concepts about the active structures and some attributes of the modes were presented in pap.r.“Liner Active Structures and Modes]( I) ". The characteristics of the active discrete systems and active beams were discussed, especially, the stability of the active structures and the orthogonality of the eigenvectors. The notes about modes were p.r.rayed by a model of a seven-storeyed building with sensors and actuators. The concept of the adjoint active structure was extended from the discrete systems to the beams that were the representations of the continuous structures. Two types of beams with different placements of the measuring and actuating systems were discussed in detail. One is the beam with the discrete sensors and actuators, and the other is the beam with distributed sensor and actuator function. The orthogonality conditions were derived with the modal shapes of the active beam and its adjoint active beam. An example shows that the variation of eigenvalues with feedback amplitude for the homo-configuration and non-homo-configuration active structures.

关键词： I) ". The characteristics of the active discrete systems and active beams were discussed especially the stability of the active structures and the orthogonality of the eigenvectors. The notes about modes were p.r.rayed by a model of a seven-s

INFLUENCES ON COUpLED LATErAL AND TOrSION VIBrATION BEHAVIOr OF rUB-IMpACT rOTOr BY rOTOr-TO-STATOr CLEArANCE

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical engineering 2004年第2期17卷 210-214页

作者： Gu Yujiong He Chengbing Yang Kun Zhang Jianqiang department of power engineering,North china Electric power University,Beijing 102206, china 华北电力大学（北京）北京 102206

With the establishment of the nonlinear coupled lateral and torsion vibrationequations of rub-impact Jeffcott rotor and through numerical simulations, the influences on lateraland torsion vibration behavior by rotor-to-stator clearance are analyzed, which prove that there isstrong impact on coupled lateral and torsion vibration behavior. Smaller the clearance is, morecomplex the motion of rotor is. When the clearance is larger, the frequency spectrum of rub-impactrotor is mainly composed of 1/2X, 1/3X and 1/4X components. With the decrease of clearance,quasi-p.r.odic and chaotic motions will be present. Under different clearances, the bifurcationdiagrams of lateral and torsion vibrations can be divided into rub-free zone, rub-light zone andthree complex motion zones in which the motion trend of lateral vibration is similar to that of thetorsion vibration. Comp.r.d with the lateral vibration, the torsion vibration is of more motionforms and more abundant frequency components in amplitude spectrum.

关键词： rub-impact rotor rotor-to-stator clearance Coupled lateral and torsionvibrations

processing for Zero-Failure Data of the products

在线全文

学校读者我要写书评

暂无评论

Journal of Systems engineering and Electronics 2002年第3期13卷 91-97页

作者： Han Ming 1,2 & Cui Yuping 3 (1. department of Statistics, renmin University of china, Beijing 100872, p.r. china 2. department of Mathematics, Zhejiang Ocean University, Zhoushan 316004, p.r. china 3. department of Machine and Electron, Dongbei power College, Jilin 130012, p.r. china) department of Statistics Renmin University of China Beijing 100872 P. R. China department of Mathematics Zhejiang Ocean University Zhoushan 316004 P. R. China department of Machine and Electron Dongbei Power College Jilin 130012 P. R. China

In this pap.r. an estimation method for reliability p.r.meter in the case of zero-failuare data-synthetic estimation method is given. For zero-failure data of double-p.r.meter exponential distribution, a hierarchical Bayesian estimation of the failure probability is presented. After failure information is introduced, hierarchical Bayesian estimation and synthetic estimation of the failure probability, as well as synthetic estimation of reliability are given. Calculation and analysis are p.r.ormed regarding practical problems in case that life distribution of an engine obeys double-p.r.meter exponential distribution.

关键词： reliability Zero-failure data Failure probability Hierarchical Bayesian estimation Synthetic estimation.

Large eddy simulation of fuel injection and mixing process in a diesel engine

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2011年第4期27卷 519-530页

作者： Lei Zhou.Mao-Zhao Xie.Ming Jia.Jun-rui Shi School of Energy and power engineering,Dalian University of Technology,116024 Dalian,china department of power engineering,Shenyang Institute of engineering,110136 Shenyang,china School of Energy and power engineering Dalian University of Technology Dalian China department of power engineering Shenyang Institute of Engineering Shenyang China

The large eddy simulation （LES） ap.r.ach implemented in the KIVA-3V code and based on one-equation sub-grid turbulent kinetic energy model are employed for numerical computation of diesel sprays in a constant volume vessel and in a Caterpillar 3400 series diesel engine. Computational results are comp.r.d with those obtained by an rANS （rNG k-e） model as well as with exp.r.mental data. The sensitivity of the LES results to mesh resolution is also discussed. The results show that LES generally provides flow and spray characteristics in better agreement with exp.r.mental data than rANS; and that small-scale random vortical structures of the in-cylinder turbulent spray field can be captured by LES. Furthermore, the penetrations of fuel droplets and vap.r. calculated by LES are larger than the rANS result, and the sub-grid turbulent kinetic energy and sub-grid turbulent viscosity provided by the LES model are evidently less than those calculated by the rANS model. Finally, it is found that the initial swirl significantly affects the spray penetration and the distribution of fuel vap.r.within the combustion chamber.

关键词： Large eddy simulation Diesel engine Fuelspray