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971.
In the present article, as a first endeavor, the wave propagation in functionally graded nanocomposites reinforced with carbon nanotubes is investigated on the basis of second-order shear deformation theory. Four different types of functionally graded nanocomposites are presented. An analytical method is used to find the circular frequencies and phase velocities. To show the accuracy of the present methodology, our results for the free vibration are compared with the results of functionally graded plates available in the literature. The influences of different parameters are also investigated on the circular frequencies and phase velocities. 相似文献
972.
Zohreh Malek-Hosseini 《先进材料力学与结构力学》2017,24(10):875-884
In this article, the dynamic response of a viscoelastic beam with moderately large deflection subjected to transverse and axial loads is studied using the first-order shear deformation theory. The von-Karman strain displacement relations and Hooke's law are used for formulation. The solution of the equations, which are a system of nonlinear partial differential equations, are obtained analytically using the perturbation technique in conjunction with the eigenfunction expansion method. The results are compared with the finite elements method. Also, a sensitivity analysis is performed, and the effects of geometrical and material properties are investigated on the response. 相似文献
973.
In the present article, higher-order shear and normal deformable plate theory together with modified couple stress theory are developed to study the bending analysis of thick functionally graded rectangular micro-plates. One material length scale parameter is used for capturing the size effects. Utilizing the variational approach and also a principle of virtual displacement, a new form of equilibrium equations and the corresponding boundary conditions are derived. It is assumed that material properties vary through the thickness according to the power law function. Finally, an analytical solution for the bending problem of a simply supported FG rectangular micro-plate is presented. 相似文献
974.
In this article, dynamic stability analysis of the viscoelastic piezoelectric polymeric nanocomposite plate reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNTs) based on modified strain gradient theory (MSGT) is explored. The viscoelastic piezoelectric polymeric nanocomposite plate reinforced is subjected to hydrothermal and electro-magneto-mechanical loadings. The viscoelastic piezoelectric polymeric nanocomposite plate is rested on viscoelastic foundation. Uniform distribution (UD), various functionally graded (FG) distribution types such as FG-V, FG-X, and FG-O are considered for single-walled carbon nanotubes (SWCNTs). The extended mixture approach is applied to estimation of the elastic properties. The equations of motion are derived by Hamilton's principle. The resonance frequency or the parametric resonance is obtained then dynamic stability region is specified. There is a good agreement between the present work and the literature result. Various parametric investigations are performed for the influences of the small scale parameters, direct and alternating applied voltage, magnetic field, viscoelastic foundation coefficients, and aspect ratios on the dynamic stability region of the viscoelastic piezoelectric polymeric nanocomposite plate. The results indicated that SWCNT agglomeration and surface stress have significant effects on the dynamic stability region and the parametric resonance. Dynamic stability region increases with increasing of thickness to width ratio, magnetic field, applied voltage, static load factor, viscoelastic foundation parameters, and surface density constant, and decreasing of length to width ratio and residual surface stress constant. Also, the dynamic stability region shifts to lower parameter resonance with increasing of temperature and moisture changes. The results can be employed for design of micro-electro-mechanical systems and nano-electro-mechanical systems. 相似文献
975.
Designing Metallic and Insulating Nanocrystal Heterostructures to Fabricate Highly Sensitive and Solution Processed Strain Gauges for Wearable Sensors 下载免费PDF全文
Woo Seok Lee Seung‐Wook Lee Hyungmok Joh Mingi Seong Haneun Kim Min Su Kang Ki‐Hyun Cho Yun‐Mo Sung Soong Ju Oh 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(47)
All‐solution processed, high‐performance wearable strain sensors are demonstrated using heterostructure nanocrystal (NC) solids. By incorporating insulating artificial atoms of CdSe quantum dot NCs into metallic artificial atoms of Au NC thin film matrix, metal–insulator heterostructures are designed. This hybrid structure results in a shift close to the percolation threshold, modifying the charge transport mechanism and enhancing sensitivity in accordance with the site percolation theory. The number of electrical pathways is also manipulated by creating nanocracks to further increase its sensitivity, inspired from the bond percolation theory. The combination of the two strategies achieves gauge factor up to 5045, the highest sensitivity recorded among NC‐based strain gauges. These strain sensors show high reliability, durability, frequency stability, and negligible hysteresis. The fundamental charge transport behavior of these NC solids is investigated and the combined site and bond percolation theory is developed to illuminate the origin of their enhanced sensitivity. Finally, all NC‐based and solution‐processed strain gauge sensor arrays are fabricated, which effectively measure the motion of each finger joint, the pulse of heart rate, and the movement of vocal cords of human. This work provides a pathway for designing low‐cost and high‐performance electronic skin or wearable devices. 相似文献
976.
Xiao Zhangru Qiao Jingsi Lu Wanglin Ye Guojun Chen Xianhui Zhang Ze Ji Wei Li Jixue Jin Chuanhong 《Nano Research》2017,10(7):2519-2526
Phosphorus atomic chains,the narrowest nanostructures of black phosphorus (BP),are highly relevant to the in-depth development of BP-based one-dimensional (1D) nano-electronics components.In this study,we report a top-down route for the preparation of phosphorus atomic chains via electron beam sculpturing inside a transmission electron microscope (TEM).The growth and dynamics (i.e.,rupture and edge migration) of 1D phosphorus chains are experimentally captured for the first time.Furthermore,the dynamic behavior and associated energetics of the as-formed phosphorus chains are further investigated by density functional theory (DFT) calculations.It is hoped that these 1D BP structures will serve as a novel platform and inspire further exploration of the versatile properties of BP. 相似文献
977.
Integrated agri-industrial systems (IAISs), such as sugarcane supply and processing systems, are complex systems and hence generally difficult to understand and manage. The large number factors in IAISs coupled with the complex interrelationships among the factors make it challenging to identify the points of intervention for improving their overall performance. Several approaches, such as the network theory and the Theory of Constraints have been used to identify important factors in systems with variations in success. This paper demonstrates a primary influence vertex approach for identifying and ranking the factors that drive the performance of IAISs. The approach is based on comprehensive causal network analyses and was tested in four relatively diverse large-scale sugarcane milling operations in South Africa. Results from the analyses were found to be consistent with the literature and external knowledge of the milling areas as at the time of the study. It is concluded that the approach can proffer a sound basis from which deeper rooted problems in systems can be identified on an ongoing basis. It is, however, recommended that the approach should be systematically compared with other relevant methods that are used to analyse complex systems. 相似文献
978.
To attain the general form of stable coalition structure, this paper addressed the problem of retailers’ coalition stability in a two-stage supply chain consisting of one supplier and multiple retailers. A profit gain function was established via introducing market gain coefficient and coalition cost coefficient for different coalition structures. Based on the function, the profit of each retailer in all kinds of coalition structures was analysed, and the general feature of a stable coalition structure was attained by the largest consistent set method and the stable set method. Furthermore, some insights were obtained. For example, stable coalition structures are equidistributed or approximate equidistributed; with supplier’s cost increasing, the size of the retailers’ coalition increases. Finally, the above conclusions are verified by numerical simulation. The results of this paper provide a reference for retailers’ coalition in a supply chain, such as automobile or Information Technology supply chain. 相似文献
979.
Yuxian Du Xi Lu Xiaoyan Su Yong Hu Yong Deng 《Quality and Reliability Engineering International》2016,32(2):737-746
Failure mode and effects analysis (FMEA) is an engineering and management technique, which is widely used to define, identify, and eliminate known or potential failures, problems, errors, and risk from the design, process, service, and so on. In a typical FMEA, the risk evaluation is determined by using the risk priority number (RPN), which is obtained by multiplying the scores of the occurrence, severity, and detection. However, because of the uncertainty in FMEA, the traditional RPN has been criticized because of several shortcomings. In this paper, an evidential downscaling method for risk evaluation in FMEA is proposed. In FMEA model, we utilize evidential reasoning approach to express the assessment from different experts. Multi‐expert assessments are transformed to a crisp value with weighted average method. Then, Euclidean distance from multi‐scale is applied to construct the basic belief assignments in Dempster–Shafer evidence theory application. According to the proposed method, the number of ratings is decreased from 10 to 3, and the frame of discernment is decreased from 210 to 23, which greatly decreases the computational complexity. Dempster's combination rule is utilized to aggregate the assessment of risk factors. We illustrate a numerical example and use the proposed method to deal with the risk priority evaluation in FMEA. The results and comparison show that the proposed method is more flexible and reasonable for real applications. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
980.
Deepening Insights of Charge Transfer and Photophysics in a Novel Donor–Acceptor Cocrystal for Waveguide Couplers and Photonic Logic Computation 下载免费PDF全文