Hodge theorem for the natural projection of complex horizontal Laplacian on complex Finsler manifolds

Let M be a compact complex manifold with a complex Finsler metric F. We define a natural projection of complex horizontal Laplacian on M: it is independent of the fiber coordinate. By using Sobolev space theory and spectral resolution theory in Hilbert space, we prove the Hodge theorem for the natural projection of complex horizontal Laplacian on M.     

Interest point detection in images using complex network analysis

This paper presents a new application of complex network theory and tools to digital image analysis and computer vision problems in order to detect interest points in digital images. We associate a weighted geometrical and fast computable complex network to each image and then we propose two different methods to locate these feature points based on both local and global (spectral) centrality measures of the corresponding network.     

Modelling viscoelastic materials whose storage modulus is constant with frequency

This paper presents a relaxation function characterising viscoelastic materials whose storage modulus is constant with frequency, and whose loss factor shows the representative peak of damping materials. This behaviour is typical of some composite materials, where the elastic constituents give the constant modulus, and the polymeric components provide the variable loss factor. The new model gives a way to provide comparative data for different materials in a form which can easily be incorporated into simulations. The physical meaning of the model parameters is defined from the analysis of the complex modulus in frequency domain. The presented relaxation function is validated by curve fitting to experimental measurements carried out on polymer concrete specimens, made of epoxy resin matrix with mineral aggregates.     

Damping Characterization and Viscoelastic Behavior of Laminated Polymer Matrix Composites Using a Modified Classical Lamination Theory

The damping property of materials can be defined as the ratio of dissipated energy over the total strain energy during the loading–unloading process, called the specific damping capacity (SDC). In this study, in order to characterize the damping properties of materials, a test plan in designed to extract the SDC of a single layer composite from hysteresis data. The theory of linear viscoelasticity incorporates a varying Young’s Modulus by using a complex stiffness modulus. Considering different lay-ups, the modified classical lamination plate theory is modified to represent both stiffness and SDC of laminates. The results are compared with experimental results for symmetric laminated specimen. This evaluation shows a very good agreement between theoretical and experimental results in the range of low frequency loading from 0.2 to 4 Hz. The complex compliance matrix changes the governing equation in to a complex form which contains both stiffness and damping properties.     

Bounds for interpolating complex effective moduli of viscoelastic materials from measured data

The complex effective moduli of viscoelastic materials can be experimentally measured by a number of techniques giving relaxation data for materials at discrete frequencies. In this paper we present a method which allows one to find bounds on the moduli of the material at the unmeasured frequencies. Our bounds can be very tight, and are, therefore, good approximations to the data. Using our bounds, experimentalists can concentrate their efforts on gathering highly accurate data at only a few frequencies and numerically generate data at other frequencies that may be of interest. Received: 10 August 1999 Accepted: 21 December 2000     

Microwave detection of molecules formed by shock wave induced reactions

The paper describes experimental investigations in a shock tube concerning the formation of new molecules using He as a driver gas and a mixture of Kr, CH and NH as driven gas, where Kr serves as diluant. By microwave absorption technique it was possible to detect HCN, CHO and CHNH as reaction products. Obviously, these molecules were formed in the plasma behind the shock wave. In addition, the “swan bands” of C have been observed with optical methods. Received 16 November 1997 / Accepted 7 May 1998     

官地水电站坝区岩体的浅表生结构

浅表生结构的研究 ,对认识河谷岩体的岩体结构特征、工程岩体结构建模及稳定性评价等具有重要意义。官地水电站坝区玄武岩体的浅表生结构极为发育 ,且其分布具有一定的规律性。本文通过对浅表生结构的发育分布及变形破裂形迹的调查分析 ,研究了浅表生结构的空间发育规律及其组合形式 ,结合地质地貌演化机制分析 ,探讨了浅表生结构的形成机制 ,建立了坝区浅表生结构的基本模式     

南海潜在地质灾害因素研究

南海是我国海洋开发的重点海区之一, 调查潜在地质灾害因素, 科学地评价海洋工程地质条件至关重要。本文根据20多年的调查资料, 研究了南海可能产生的地质灾害类型、规模、分布特征、形成机制和诱发因素, 分析了南海地质灾害因素主要特征, 提出今后研究方向, 为科学开发海洋资源提供依据。     

Hydrodynamics of a biologically inspired tandem flapping foil configuration

Numerical simulations have been used to analyze the effect that vortices, shed from one flapping foil, have on the thrust of another flapping foil placed directly downstream. The simulations attempt to model the dorsal–tail fin interaction observed in a swimming bluegill sunfish. The simulations have been carried out using a Cartesian grid method that allows us to simulate flows with complex moving boundaries on stationary Cartesian grids. The simulations indicate that vortex shedding from the upstream (dorsal) fin is indeed capable of increasing the thrust of the downstream (tail) fin significantly. Vortex structures shed by the upstream dorsal fin increase the effective angle-of-attack of the flow seen by the tail fin and initiate the formation of a strong leading edge stall vortex on the downstream fin. This stall vortex convects down the surface of the tail and the low pressure associated with this vortex increases the thrust on the downstream tail fin. However, this thrust augmentation is found to be quite sensitive to the phase relationship between the two flapping fins. The numerical simulations allows us to examine in detail, the underlying physical mechanism for this thrust augmentation.