Identification of open crack of beam using model based method

This research aims at identifying the position and depth of the open transverse crack of the beam using the model based method. The stiffness matrix of the cracked beam element and the basic principle of the model based method are introduced. It is discussed to estimate the generalized displacement of all nodes of the beam by the measured displacements of a few degrees of freedom. The relative change rate of the equivalent external load between the intact and cracked elements is compared with that of mode shape, nature frequency and displacement amplitude between the intact and cracked beam. The position and depth of the crack are identified by the model based method in two cases. In first case, the measured displacement is assumed not to include noise. The identification results based on the actual displacement and rotation of all nodes are compared with the results using the estimated generalized displacement. In second case, the measured displacement includes noise and the generalized displacement of all nodes is estimated by the displacement of two measurement points. The simulation results shown there is no error to identify the position, the relative depth identification error of the crack with 1 μm depth is 2.34 % without noise, and the relative depth identification error of the crack with 200 μm depth could be down to about 5 % with the energy signal to noise ratio being about 7.00 before denoising

Life estimation of the beam with normal distribution parameters and subjected to cyclic load

This research aims at estimating the life of the beam with normal distribution parameters and subjected to cyclic load. It is tested by Monte-Carlo simulation that the generalized displacement and velocity are normally distributed when the coefficient of variation (CV) of the random parameter is small (generally CV≤ 0.01). The random perturbation method is employed to estimate the mean and variance of the generalized displacement and velocity. The random dynamic stress and its derivative with respect to the time t of the beam is formulated according to the shape function of beam element and the stress equation in a Euler-Bernoulli beam. Their mean, variance and correlation coefficient are given using the first-order approximation in a Taylor series. Based on Palmgren-Miner rule, the expected cumulative damage equation is given and is used to estimate the life where the random dynamic stress is non-stationary and follows the normal distribution with the nonzero mean at any time t. The presented method could also estimate the life of other structure or component which has several normal random parameters, is subjected to cyclic load and obeys the linear dynamics and elastic theory when the random parameter’s CV is small

Simplifying the Creation of Hollow Metallic Nanostructures: One-Pot Synthesis of Hollow Palladium/Platinum Single-Crystalline Nanocubes

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Chem & Chem Engn, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Coll Chem & Chem Engn, Dept Chem, Xiamen 361005, Peoples R China 电子邮件地址: [email protected],20871100,20721001 MSTC,2009CB930703 Chinese Ministry of Education 108077 RFDP 200803841010 Key Scientific Project of Fujian Province of China 2009HZ1010

An Assembly Route to Inorganic Catalytic Nanoreactors Containing Sub-10-nm Gold Nanoparticles with Anti-Aggregation Properties

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Xiamen 361005, Peoples R China 3. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected], [email protected] Ministry of Education,108077 NNSFC,20871100 20721001 20423002 MSTC,2007CB815303 2009CB930703 NFFTBS,J063042

Nonaqueous Production of Nanostructured Anatase with High-Energy Facets

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Xiamen 361005, Peoples R China 3. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: [email protected], [email protected] solution-based synthesis is the most powerful and economic method to create nanostructured anatase TiO2, under those synthesis conditions the {101} facets are the most thermodynamically stable, making it difficult to create anatase nanomaterials with a large percentage of high-energy {001} or {010} facets exposed. Here, we report a facile nonaqueous synthetic route to prepare anatase nanosheets with exposed {001} facets and high-quality rhombic-shaped anatase nanocrystals with a large percentage of exposed {010} facets. Including adscititious water in the nonaqueous synthesis and eliminating the use of carboxylic acid type capping agents are the two keys to integrating the structural diversity from aqueous systems into large-quantity synthesis in nonaqueous systems. The nanostructured TiO2 that we prepared exhibits conspicuous activity in the photocatalytic degradation of organic contaminants.Chinese Ministry of Education 108077 NNSFC 20871100 20721001 20423002 MSTC 2007CB815303 2009CB93070

Gradual Reliability Sensitivity Analysis of Mechanical Part Considering Preventive Maintenance

A lot of mechanical parts are subject to failure due to the deterioration. Usually the preventive maintenance is taken to ensure the safety and reliability. Therefore, it is very important to study the gradual reliability design of the mechanical part for improving the gradual reliability of the mechanical system under the condition of considering the preventive maintenance. Beta distribution is employed to describe the randomness of the mechanical part state after the preventive maintenance. The deterioration process of the mechanical part is modeled using the nonstationary Gamma process. The gradual reliability model before the first preventive maintenance is proposed according to the gradual failure principle and using the initial state distribution and the properties of Gamma process. Then, the gradual reliability model between any two times of preventive maintenance is also derived. Subsequently, the sensitivity equations of the proposed gradual reliability model to each parameter are given. The application process and practicality of the proposed approach are described by a numerical example. This work solved the problem where the maintenance has not been well considered in the reliability design of the mechanical part and contributed to the theory and method of improving the safety and reliability operation of the mechanical system

Breeding scheme showing the development of N9116H and N9116M.

<p>Breeding scheme showing the development of N9116H and N9116M.</p

Morphologic traits of M8003, Austrian rye, N9116H and N9116M.

<p>a Plant of M8003, Austrian rye, N9116M and N9116H; b Spikes of M8003, Austrian rye, N9116M and N9116H; c Spikelets and kernels of M8003, Austrian rye, N9116H and N9116M; d Resistance of M8003, Austrian rye, N9116H and N9116M for powdery mildew and stripe rust. 1–4 in figures represent M8003, Austrian rye, N9116M and N9116H, respectively.</p

Directional Migration of Vascular Smooth Muscle Cells Guided by a Molecule Weight Gradient of Poly(2-hydroxyethyl methacrylate) Brushes

Directional migration of cells mediated by gradient cues <i>in vitro</i> can mimic the corresponding biological events <i>in vivo</i> and thereby provides a way to disclose the cascade responses in tissue regeneration processes and to develop novel criteria for design of tissue-inductive biomaterials. In this work, a molecular weight gradient of poly­(2-hydroxyethyl methacrylate) (PHEMA) brushes with a thickness ranging from 3 to 30 nm and slopes of 0.8–3.2 nm/mm were fabricated by using surface-initiated atom transfer radical polymerization (ATRP) and a dynamically controlled reaction process. The PHEMA gradients were characterized by X-ray photoelectron spectrometry (XPS) and ellipsometry. The adhesion number, spreading area, adhesion force, and expression of focal adhesion and actin fibers of vascular smooth muscle cells (VSMCs) decreased along with the increase of the PHEMA brushes length. The VSMCs exhibited preferential orientation and enhanced directional migration toward the direction of reduced PHEMA thickness, whose extent was dependent on the gradient slope and polymer thickness. Most of the cells were oriented, and 87% of the cells moved directionally at the optimal conditions