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LINEAR ACTIVE STRUCTURES AND MODES (Ⅱ) —DISCRETE SYSTEMS AND BEAMS

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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 paper “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 portrayed 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 portrayed by a model of a seven-s

Wave-current forces on bipiles in parallel array

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Acta Oceanologica Sinica 1992年第3期11卷 453-462页

作者： Li Yucheng, Wang Fenglong and Wang Hongrong department of civil engineering, Dalian university of Technology, Dalian 116024, China

-The inline and lift forces on bipiles in parallel array induced by both irregular waves and currents were investigated experimentally in this paper. The characteristics in both time and frequency domains of inline, lift and resultant forces as well were analyzed. The grouping effect coefficients of inline and resultant forces on two piles related to KC number and relative spacing parameters are given. A comparison of the magnitude and direction of resultant forces on two piles in parallel array with the corresponding values for single cylinder is also made.

关键词： Wave-current forces on bipiles in parallel array

Irregular　wave－induced　seepage　action　on　cylinders　resting　on　rubble　mound　foundation

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Acta Oceanologica Sinica 1996年第3期15卷 377-396页

作者： Qiu Dahong and Yang Gang (department of civil engineering.Dalian university of TechnolOgy, Dalian 116023, China) department of civil engineering Dalian University of Technology Dalian 116023 China

In this paper, the irregular wave-induced seepage action on cylinders resting on rubble mound foundatoin (RMF) is studied by means of finite element method (FEM). The hydraulic resistance inside RMF is assumed to satisfy the nonlinear Forchheimer's equation and the seepage in the scabed is also considered. Model tests show good agreementwith the numerical results. The influence of several main parameters is discussed on the basis of vast calculations. In addition, the ratio of seepage forces, induced by regular and irregular waves respectively, is analyzed and thus a computaional method is put forward for practical engineering application to simplify the calculation of irregular wave-induced seepage forces.

关键词： Wave-induced seepage forces irregular wave rubble mound foundation

THEORETICAL STUDIES ON MICROBUCKLING MODE OF ELASTIC MEMORY COMPOSITES

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Acta Mechanica Solida Sinica 2010年第1期23卷 20-28页

作者： Zhengdao Wang Zhengfa Li Zhiyuan Xiong Linyun Wang(department of Mechanics,School of civil engineering,Beijing Jiaotong university,Beijing 100044,China) [a] department of Mechanics School of Civil Engineering Beijing Jiaotong University Beijing 100044 China

Elastic memory composites （EMCs） have great potential applications in future deployable space structures due to their high packaging strain and shape memory characteristics. Microbuckling of compressed fibers is the primary deformation mechanism of such structures to receive a higher packaging strain than that of traditional fiber-reinforced composites. In order to have a better understanding of such deformation mechanism, the microbuckling model of EMC laminates under bending is analyzed firstly. Then the theoretical critical microbuckling parameters are predicted, which are compared with experimental observations and other models.

关键词： elastic memory composite deployable structure microbuckling model

A NOTE ON THE NARROW OPEN CHANNEL RESONANCE

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Journal of Hydrodynamics 2002年第1期14卷 29-37页

作者： Miao Guo-ping (School of Naval Architecture and Ocean engineering, Shanghai Jiaot ong university, Shanghai 200030, China) H.Ishida, T.Saitoh (department of civil engineering, Kanazawa university, Japan) School of Naval Architecture and Ocean engineering Shanghai Jiaotong University Shanghai 200030 China department of civil engineering Kanazawa University Japan

A narrow open channel resonant phenomenon, newly found by the authors in corresponding numerical calculations , was proved to exist based on the method of matching asymptotic expansions for three different channel configurations. It is shown that the resonant wave numbe rk emerges around kL=nπ, n=1,2,3,…∞ with a corresponding frequency s hift, where L is the length of the channel. It is also clear that the resona nce in a narrow open channel is an essential property of a channel as long as it is uniformly narrow.

关键词： narrow open channel resonance the method of matching asymptotic expansions wave diffraction multiple bodies

A　HYBRID　METHOD　FOR　THE　SIMULATION　OF　WAVE　SPECTRUM　TRANSFORMATION　AND　BREAKING　PHENOMENA　ON　A　SLOPE

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Journal of Hydrodynamics 1995年第2期7卷 76-83页

作者： Li Yu-cheng Dong Guo-hai(department of civil engineering Dalian university of Technology,Dalian 116023, P. R. China) Dalian Univ of Technology Dalian China

In shallow water, during the wave propagation the nonlinear and wave breaking effect must be taken into account. In this peper a simplified hybrid method was proposed, in which a combined frequency and time domain analysis was used. By using authors' method, the process are quite simple and easy to run on a PC computer, but the nonlinear and wave bleaking effect was still been considered. The computed data coincide authors' test results quite well.

关键词： wave tranformation wave breaking numerical simulstion

Effect of Limestone Powder and Fly Ash on Magnesium Sulfate Resistance of Mortar

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Journal of Wuhan university of Technology(Materials Science) 2010年第4期25卷 700-703页

作者：刘数华 State Key Laboratory of Water Resources and Hydropower engineering Science Wuhan University

The effect of limestone powder and fly ash on magnesium sulfate resistance of mortar was studied by testing on the strength, expansion and hydration products of the specimens stored in MgSO4 solution at certain periods. The experimental results show that the strength of mortar stored in MgSO4 solution increases a little before 28 d, but decreases fast subsequently. The more the contents of limestone powder and fly ash, the less the strength losses. Mortar swells in the MgSO4 solution with the soaking time. And the more the contents of limestone powder and fly ash, the less the expansion rate is. The expansion or strength loss of mortars results from the expansion of gypsum, as well as the loss of Ca（OH）2 and other hydration products of cement. The magnesium sulfate resistance of the mortars containing limestone powder and fly ash is high.

关键词： limestone powder fly ash mortar magnesium sulfate resistance

Edge Effect Correction in the S-A Method for Geochemical Anomaly Separation

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Journal of China university of Geosciences 2004年第4期15卷 379-387页

作者： Ge Yong department of Earth and Atmospheric Science, York university, toronto, ON, M3J 1P3, canada State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences & Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Cheng Qiuming department of Earth and Atmospheric Science, York university, toronto, ON, M3J 1P3, canada Earth Systems and Mineral Resource engineering Lab, China university of Geosciences, Wuhan 430074, China Zhang Shenyuan department of Earth and Atmospheric Science, York university, toronto, ON, M3J 1P3, canada department of Resource and Earth Science, China university of Mining & Technology, Beijing 100083, China department of Earth and Atmospheric Science York University Toronto ON M3J 1P3 Canada State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences & Natural Resources Research Chinese Academy of SciencesBeijing 100101China department of Earth and Atmospheric Science York University Toronto ON M3J 1P3 Canada Earth Systems and Mineral Resource engineering Lab China University of Geosciences Wuhan 430074 China department of Earth and Atmospheric Science York University Toronto ON M3J 1P3 Canada department of Resource and Earth Science China University of Mining & Technology Beijing 100083 China

Anomaly separation using geochemical data often involves operations in the frequency domain, such as filtering and reducing noise/signal ratios. Unfortunately, the abrupt edge truncation of an image along edges and holes (with missing data) often causes frequency distribution distortion in the frequency domain. For example, bright strips are commonly seen in frequency distribution when using a Fourier transform. Such edge effect distortion may affect information extraction results; sometimes severely, depending on the edge abruptness of the image. Traditionally, edge effects are reduced by smoothing the image boundary prior to applying a Fourier transform. Zero-padding is one of the most commonly used smoothing methods. This simple method can reduce the edge effect to some degree but still distorts the image in some cases. Moreover, due to the complexity of geoscience images, which can include irregular shapes and holes with missing data, zero-padding does not always give satisfactory results. This paper proposes the use of decay functions to handle edge effects when extracting information from geoscience images. As an application, this method has been used in a newly developed multifractal method (S-A) for separating geochemical anomalies from background patterns. A geochemical dataset chosen from a mineral district in Nova Scotia, canada was used to validate the method.

关键词： edge effect correction fractal modeling spatial information extraction zero-padding decay functions.

A NEW METHOD IN GROUNDWATER FLOW MODELING

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Journal of Hydrodynamics 2009年第2期21卷 245-254页

作者： MA Xiu-yuan LI Shu-guang ZHU Wei-shen School of civil engineering Shandong University Jinan 250061 China department of civil and Environmental engineering Michigan State University East Lansing Michigan 48834USA

One of the challenges in groundwater modeling is the prediction of hydraulic head related to local stress fluctuations with a regional scale model. Typical applications of numerical models require extensive field information for input data and for calibration If we can model the change directly, we may not have to know all the modeling parameters because sometimes the changes only depend on fewer parameters. In this article, we present an improved methodology for groundwater modeling related to local stress fluctuations using a perturbation approach. Our results demonstrate that this approach is capable of matching an exact solution for drawdown in both confined and unconfined aquifers. The results suggest that this perturbation method can provide an accurate representation of head in a large-scale hydrogeological system.

关键词： groundwater modeling local stress fluctuations perturbation method iteration scheme