Assessment of “change in flexibility method” in structural health monitoring systems

The modern structural diagnosis process is rely on vibration characteristics to assess safer serviceability level of the structure. This paper examines the potential of change in flexibility method to use in damage detection process and two main practical constraints associated with it. The first constraint addressed in this paper is reduction in number of data acquisition points due to limited number of sensors. Results conclude that accuracy of the change in flexibility method is influenced by the number of data acquisition points/sensor locations in real structures. Secondly, the effect of higher modes on damage detection process has been studied. This addresses the difficulty of extracting higher order modal data with available sensors. Four damage indices have been presented to identify their potential of damage detection with respect to different locations and severity of damage. A simply supported beam with two degrees of freedom at each node is considered only for a single damage cases throughout the paper.

Monodisperse sub-10 nm gold nanoparticles by reversing the order of addition in Turkevich method - The role of chloroauric acid

The Turkevich method for synthesizing gold nanoparticles, using sodium citrate as the reducing agent, is renowned for its ability to produce biocompatible colloids with mean size >10 nm. Here we show that monodisperse gold nanoparticles in the 5-10 nm size range can be synthesized by simply reversing the order of addition of reactants, i.e. adding chloroauric acid to citrate solution. Kinetic studies and electron microscopic characterization revealed that the reactivity of chloroauric acid, initial molar ratio of citrate to chloroauric acid (MR), and reaction mixture pH play an important role in producing monodisperse gold nanoparticles. Reversing the order of addition also enhanced the stabilization of nanoparticles at high MR values. Remarkably, the system exhibits a `memory' of the order of addition, even when the timescale of mixing is much shorter than the timescale of synthesis. (C) 2011 Elsevier Inc. All rights reserved.

A non-intrusive in situ method of optical beam profiling in LCOS-based optical fiber switches

This paper proposed a non-intrusive method of measuring the optical beam profile at the surface of the liquid crystal on silicon (LCOS) device in an optical fiber switch. This method is based on blazed grating and can be employed in situ (on-line) for two-dimensional beam profiling in the LCOS-based optical fiber switches without introducing additional components or rearranging the system. The measured beam radius was in excellent agreement with that measured by the knife-edge technique. © 2013 Elsevier Ltd.

An efficient in vitro method for mass propagation of Potentilla potaninii wolf

This study reports a method for high-frequency shoot organogenesis and plant establishment of Potentilla potaninii Wolf. Hypocotyl and cotyledon explants of P. potaninii were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of benzyladenine (BA) and alpha-naphthaleneacetic acid (NAA) to induce adventitious shoot formation for micropropagation. The highest frequency of adventitious shoot regeneration was achieved from hypocotyl and cotyledon explants grown on MS medium supplemented with 5.0 mg l(-1) BA and 1.0 mg l(-1) NAA. The regenerated shoots rooted most efficiently on half-strength MS medium supplemented with 1.0 mg l(-1) NAA and 0.5 mg l(-1) indole-3-acetic acid or indole-3-butyric acid. The acclimatized plants with normal morphology and growth characters flowered and set seeds in the following year.

The progress in the method of immobilizing biomolecules for piezoelectric immunosensors

The working principle of piezoelectric mass sensor is generally introduced. Tbe recent progress about the method of immobilizing biomolecule, such as antigen, antibody etc. onto piezoelectric crystal surfaces has been reported, including the way of directly immobilizing biomolecules, and immobilizing them using protein A(or protein G), polymer, silianizition agent, SAM technique, LB monolayer technique etc.. At last, some recent trends of the field has been outlined.

High energy resolution fluorescence detection XANES - an in situ method to study the interaction of adsorbed molecules with metal catalysts in the liquid phase

The change in the Pt electronic structure following the adsorption of an a,ß-unsaturated aldehyde and ketone was followed by in situ HERFD-XANES in the liquid phase. The resulting shift in the Pt Fermi energy is in good agreement with the molecule adsorption energy trends calculated by DFT and provides insight into the reaction selectivity.

Temporal constraint satisfaction in matrix method

Constraint satisfaction is a challenging problem in Interval Algebra (IA). So there are many efforts to attack this problem. After building a matrix method to deal with temporal reasoning problems, we develop basic techniques for applying the matrix method to constraint satisfaction in this paper. Thus, the propagating rules and the algorithms of 3- and path-consistency are studied. If our matrix method is used, then the temporal constraint satisfaction problem can be transformed into a problem that can be effectively solved.

Multiphase material modelling by multiscale particle-in-cell method

A particle-based method for multiscale modeling of multiphase materials such as Dual Phase (DP) and Transformation Induced Plasticity (TRIP) steels has been developed. The multiscale Particle-In-Cell (PIC) method benefits from the many advantages of the FEM and mesh-free methods, and to bridge the micro and macro scales through homogenization. The conventional mesh-based modeling methods fail to give reasonable and accurate predictions for materials with complex microstructures. Alternatively in the multiscale PIC method, the Lagrangian particles moving in an Eulerian grid represent the material deformation at both the micro and macro scales. The uniaxial tension test of two phase and three-phase materials was simulated and compared with FE based simulations. The predictions using multiscale PIC method showed that accuracy of field variables could be improved by up to 7%. This can lead to more accurate forming and springback predictions for materials with important multiphase microstructural effects.

An in situ method for the study of strain broadening using synchrotron X-ray diffraction

A tensonometer for stretching metal foils has been constructed for the study of strain broadening in X-ray diffraction line profiles. This device, which is designed for use on powder diffractometers and was tested on Station 2.3 at Daresbury Laboratory, allows in situ measurements to be performed on samples under stress. It can be used for data collection in either transmission or reflection modes using either symmetric or asymmetric diffraction geometries. As a test case, measurements were carried out on an 18 µm-thick copper foil experiencing strain levels of up to 5% using both symmetric reflection and symmetric transmission diffraction. All the diffraction profiles displayed peak broadening and asymmetry which increased with strain. The measured profiles were analysed by the fundamental-parameters approach using the TOPAS peak-fitting software. All the observed broadened profiles were modelled by convoluting a refineable diffraction profile, representing the dislocation and crystallite size broadening, with a fixed instrumental profile predetermined using high-quality LaB6 reference powder. The deconvolution process yielded `pure' sample integral breadths and asymmetry results which displayed a strong dependence on applied strain and increased almost linearly with applied strain. Assuming crystallite size broadening in combination with dislocation broadening arising from f.c.c. a/2〈110〉{111} dislocations, the variation of mechanical property with strain has been extracted. The observation of both peak asymmetry and broadening has been interpreted as a manifestation of a cellular structure with cell walls and cell interiors possessing high and low dislocation densities.