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This paper proposes a stable nodal integration method for analyzing coupling problems of electromagnetic field and mechanical field using linear triangular mesh. For transient electromagnetic field analysis, the node-based smoothed solution is firstly formulated to compute system matrices, and then the equivalent smoothing domain and temporal integration points are constructed to achieve a stable nodal integration method (SNIM), whose coefficient matrix is finally computed using the smoothed shape function derivatives together with the variance terms over the equivalent smoothing domain associated with nodes of the mesh. For dynamic large-deformation analysis, the node-based smoothed finite element method (NS-FEM) is utilized after testifying its stability and effectiveness in thin-walled structures of electromagnetic forming (EMF) process. Furthermore, by treating the morphing region as a static mechanical problem, a weighted elastomer method is presented to accomplish the mesh updating in sequential coupling simulation. Finally, it turns out that the proposed methodologies can be applied successfully to simulate EMF process, and numerical examples for both tube bulging and tube compression are investigated to demonstrate the validity, accuracy and efficiency of the proposed methods.

The widely-used numerical modeling approaches such as the finite element method (FEM) and statistical energy analysis (SEA) often have limited applicability to the transmission loss prediction in mid-frequency range. In this paper, a novel hybrid edge-based smoothed FEM coupled with statistical energy analysis (ES-FE-SEA) method is proposed to further improve the accuracy of “mid-frequency” transmission loss predictions. The application of ES-FEM will “soften” the well-known ‘‘overly-stiff’’ behavior in the standard FEM solution and reduce the inherent numerical dispersion error. While the SEA approach deals with the physical uncertainty in the relatively higher frequency range. The plate of interest is appropriately described by an ES-FEM model, due to its relative robustness to perturbations. Its adjacent reverberation cavities are modeled by employing the SEA approach, because of their high model density. The coupling and interaction between SEA subsystems and the FE subsystem is governed by the “reciprocity relationship” theorem. A standard numerical example for benchmarking is examined and excellent agreement was achieved between the prediction and reference results. The proposed ES-FE-SEA is also verified by various numerical examples. The method is finally applied to the modeling a complicated engineering problem–acoustic fields on both sides of the front windshield in a passenger car.

Combined isogeometric analysis (IGA) and shape optimization, this paper provides a method that can accurately analyze Tailor Rolled Blanks (TRB) and optimize its thickness profile continuously. While existed traditional methods can hardly solve these problems. TRB has a continuous transition between the thick and thin and a better surface quality. We found in IGA, two-dimension NURBS could present TRB geometry model exactly, but Kirchhoff shell element whose control points are allocated different thicknesses could not simulate TRB effectively. So, this paper uses three-dimension NURBS element to exactly present and accurately analyze TRB. It could avoid error caused by inaccurate presentation of geometry model and decrease error caused by solution field (displacement) approximation in numerical computation. Meanwhile, the positions of control points are taken as design variables in process of optimizing thickness profile. It can avoid the appearance of "unrealistic" shape and save lots of time spent in traditional tediously mesh updating as well as having better accuracy. This method makes accurate analysis and continuous thickness optimization of TRB become possible. It pushes the development of TRB engineering and extends the applications of IGA optimization. Several examples including benchmarks and application used the proposed method verified its effectivity, reliability and efficiency.

This paper presents a curvature-constructed triangular element for static, free vibration and explicit dynamic analyses of shell structures by using a continuity re-relaxed technique. In the present method, the formulation is based on the classical thin shell theory, and only the translational displacements are treated as the filed variables that are assumed piecewisely linear. A set of three-node triangular background cells is adopted to discretize the problem domain. The curvature field in an element is constructed using the continuity re-relaxed technique, which can relax the continuity requirement of the trial function. The membrane strain filed is formulated same as the practice of standard FEM. Based on the principle of virtual work, the discertized system equations are finally formed. As the rotational displacements are not considered as the basic degrees of freedom, the essential boundary conditions of this part are imposed in the process of forming the curvature field. In order to validate the efficiency and accuracy of the present method, several numerical examples are studied. The results demonstrate that the present formulation can achieve very stable and accurate solutions with the less consuming of CPU time.

Summary Predicting the frequency response of a complex vibro-acoustic system becomes extremely difficult in the mid-frequency regime. In this work, a novel hybrid face-based smoothed finite element method/statistical energy analysis (FS-FEM/SEA) method is proposed, aiming to further improve the accuracy of ‘mid-frequency’ predictions. According to this approach, the whole vibro-acoustic system is divided into a combination of a plate subsystem with statistical behaviour and an acoustic cavity subsystem with deterministic behaviour. The plate subsystem is treated using the recently developed FS-FEM, and the cavity subsystem is dealt with using the SEA. These two different types of subsystems can be coupled and interacted through the so-called diffuse field reciprocity relation. The ensemble average response of the system is calculated, and the uncertainty is confined and treated in the SEA subsystems. The use of FS-FEM ‘softens’ the well-known ‘overly stiff’ behaviour in the standard FEM and reduces the inherent numerical dispersion error. The proposed FS-FEM/SEA approach is verified and its features are examined by various numerical examples. Copyright © 2015 John Wiley & Sons, Ltd.

A new smoothed finite element method (S-FEM) is proposed using hybrid smoothing operations based on nodes and edges of the mesh for static and free vibration analyses of plates governed by the Reissner---Mindlin plate theory. In the present approach, both the node-based smoothed finite element method (NS-FEM) and edge-based smoothed finite element method (ES-FEM) are utilized in a careful designed manner to overcome the shear locking. The formulations use 3-node triangular elements for easy automatic mesh creation, and linear interpolation functions are used for simplicity and robustness. The bending strains field are smoothed by the means of gradient smoothing technique over smoothing domains constructed by element edges, while the shear strains filed is smoothed based on the combination of NS-FEM and ES-FEM with a proper weightage controlled by a coefficient. A simple formula is developed for automatic selection of the coefficient by considering mesh size and thickness of the plate. For easy reference, the present technique is termed as NS+ES-FEM. The numerical examples demonstrate that the proposed method passes the shear-locking test and improves accuracy of the solution.

In this paper, an edge-based smoothed finite element method (ES-FEM) is further formulated to deal with the thermo-mechanical analyses of functionally graded cylindrical vessels. In the ES-FEM, the problem domain is first discretized into triangular elements, and the edge-based smoothing domains are further formed along the edges of the triangular meshes. In order to improve the accuracy, the stiffness matrices are calculated using the strain smoothing technique in these smoothing domains. The FGM cylindrical vessels are assumed to be made of ceramics and metals whose volume fractions vary continuously in the radius direction according to a power law. Different material model and thermal boundary conditions are studied. The present formulation is straight-forward and no penalty parameters or additional degrees of freedom are utilized. Numerical examples are given to demonstrate the effectivity of ES-FEM for thermo-mechanical analysis of functionally graded cylindrical vessels.

This paper applies the boundary face method (BFM) to solve both steady-state and unsteady-state heat conduction problems in the dam construction. Instead of employing the isoparametric elements as in the boundary and finite element methods, the BFM uses directly geometric models from CAD packages to avoid geometric errors for any complex structures. Moreover, the variable approximations and the boundary integration are all performed in the parametric space of the boundary surfaces, which means that the elements and integral patches are defined in the parametric space. A numerical example of steady-state analysis presented in this paper is a concrete dam structure which consists of several blocks. The example of unsteady-state analysis, which concerns a single block with several holes in it, has also been presented to illustrate the validity and the efficiency of the proposed method.

A complex product often requires a high machining precision. This is often achieved by a close-loop machining process to be carried out in several stages, and the measurements, fixture adjustments, and feedback or feed-forward control are inserted after each of these stages. The Complex Product Machining Process (CPMP) Capability Index (CPMPCI) is affected by the control and adjustments in a CPMP, and hence the calculation results of CPMPCI can be used as references to select a proper CPMP. In this paper, we present a novel calculation method of CPMPCI as quality control and improvement technology in a CPMP. A linear model is proposed for describing the variation propagation effect throughout all stages in a CPMP, and an observation model with the pre-specified control and adjustment strategy is employed to calculate the process mean and variation during a CPMP. Finally, through application of Taguchi's quality loss function, the CPMPCI calculation method is derived. The feasibility and effectiveness of t...

In this paper, bending and vibration analysis of laminated composite plates is carried out using a novel triangular composite plate element based on an edge-based smoothing technique. The present formulation is based on the first-order shear deformation theory, and the discrete shear gap (DSG) method is employed to mitigate the shear locking. The smoothed Galerkin weak form is adopted to obtain the discretized system equations, and edge-based smoothing domains are used for the numerical integration to improve the accuracy and the convergence rate of the method. The present formulation is coded and used to solve various example problems of bending and free vibration of laminated composite plates. It is found that the present method can provide excellent results with a wide range of thickness and is free of shear locking.

In automotive industry, structural optimization for crashworthiness criteria is of special importance in the early design stage. To reduce the vehicle design cycle, metamodeling techniques have become so widespread... In this study, a time-based metamodeling technique is proposed for the vehicle design. The characteristics of the proposed method are the construction of a time-based objective function and establishment of a metamodel by support vector regression (SVR). Compared with other popular metamodel-based optimization methods, the design space of the proposed method is expanded to time domain. Thus, more information and features can be extracted in the expanded time domain. To validate the performance of the time-based metamodeling technique, cylinder impacting and full vehicle frontal collision are optimized by the proposed method. The results demonstrate that the proposed method has potential capability to solve the crashworthiness vehicle design.

A typical fan desulphurization measuring points (failure-prone region), according to measurement data on many occasions, its failure to find the development trend of the equipment malfunction and made more accurate judgments. At the same time, the preparation of the equipment, the corresponding vibration diagnostic criteria and common fault identification intelligent system and continuously updated to facilitate site inspection personnel equipment vibration condition monitoring work and improve their equipment to grasp the operation of the accuracy and efficiency.

In the present paper, a Kriging-based metamodeling technique is used to minimize the risk of failure in a sheet metal forming process. The Kriging-based models are fitted to data that are obtained for larger experimental areas than the areas used in low-order polynomial regression metamodels. Therefore, computational time and memory requirement can be an obstacle for Kriging for data sets with many observations. To improve the usability of the Kriging-based metamodeling techniques, a parallel intelligent sampling approach: boundary and best neighbor searching (BBNS) (Wang et al., J Mater Process Technol 197(1–3):77–88, 2008a) is suggested. Compared with the serial BBNS version, the sampling procedure is performed synchronously. Thus, larger sample size should be considered for real-life problems when multiple processors are available. Furthermore, the parallel strategy is prone to converge based on more samples. The performance of the parallel approached is verified by means of nonlinear test functions. Moreover, the drawbead design in sheet metal forming is successfully optimized by the parallel BBNS approach and Kriging metamodeling technique. The optimization results demonstrate that the parallel BBNS approach improves the applicability of the Kriging metamodeling technique substantially.

The least square support vector regression (LS-SVR) metamodel technique is proposed for sheet metal forming optimization. The major advantage of proposed approach is to build metamodel by consideration of empirical risk minimization (ERM) and structure risk minimization (SRM). In order to construct robust and accurate metamodel based LS-SVR, suitable quantity and intervals of samples are recommended. Thus, a parallel intelligent sampling scheme based on a boundary and best neighbor searching method (BBNS) is proposed to improve the efficiency and accuracy of metamodel. The BBNS was suggested and corresponding practical engineer problems were successfully solved by Hu and Li [Hu W, Li GY, Zhong ZH. Optimization of sheet metal forming processes by adaptive response surface based on intelligent sampling method. J Mater Process Technol 2008;197(1–3):77–88; Hu Wang, Li GY, Li Enying, Zhong ZH. Development of metamodeling based optimization system for high nonlinear engineering problems. Adv Eng Software 2008;39(8)629–45]. To increase the efficiency of metamodel based optimization method, the parallel architecture is implemented for BBNS due to its drawbacks. For validation of developed method, both of serial and parallel BBNS scheme are applied for the nonlinear function. The parallel BBNS is also verified to be an accuracy and efficiency scheme. Finally, the practical nonlinear engineering problems are optimized by suggested methodology and satisfied results are also obtained.

Temperature characteristics and thermal resistance of InGaAs/GaAs laser diode (LD) is investigated from below to beyond the lasing threshold. Spectrally-resolved emission measurements show that the heat generated in the active region is induced by the radiative energy transfer of free carriers. Below the lasing threshold, nonradiative recombination induces large heat generation in the active region. Beyond the lasing threshold, Joules heating due to the series resistance of the LD dominates the heating response. The dependence of the associated thermal resistance on different bonding configurations and its correlation with the output power is also discussed. Epi-side up and epi-side down bonding of LDs reduces the device temperature by ~ 30% and ~ 50%, respectively.

Based on an optimized bonding technique for semiconductor lasers, parametric investigations of different bonding configurations were performed using AuSn solder. No abrupt electrical degradation was observed for both face-up and face-down bonding configurations. The typical optical output achieved for face-up and face-down bonding approach was about 100 mW/facet and 150 mW/facet, respectively. Face-up bonded LDs exhibited a steady differential quantum efficiency ηD of ∼ 0.425 mW/mA before gradual degradation at 200 mA, while face-down bonded LDs improved its performance beyond 350 mA. The characteristic temperature T0 also improved to as much as 643 K for face-down bonded LDs. Spectrally-resolved emission measurement showed that the temperature rise in unbonded, face-up bonded and face-down bonded LDs were approximately 11, 7–8 and 2–3 °C, respectively. These investigations showed that the improved performances for face-down bonding approach compared to face-up approach were due to better thermal management.

In this paper we proposed a block cryptosystem based on 1d-k5 Chain C CA, by alternatively iterating leftand right-toggle chain rules, this kind of encryption is achieved by backward iteration and decryption is realized via forward iteration. From theory proof, we can ensure the security of the cryptosystem, and make mostly confusion and diffusion function. Experimant shows that this cryptosystem has a large key space and good scrambling effect and can resist brute attack and differential attack effectively. Keywords-cellular automata (CA); Chaos, encryption; cryptanalysis

ZnO and ZnO:Zn powder phosphors were prepared by the polyol-method followed by annealing in air and reducing gas, respectively. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectra (XPS), electron paramagnetic resonance (EPR), and photoluminescence (PL) and cathodoluminescence (CL) spectra, respectively. The results indicate that all samples are in agreement with the hexagonal structure of the ZnO phase and the particle sizes are in the range of 1-2 microm. The PL and CL spectra of ZnO powders annealed at 950 degrees C in air consist of a weak ultraviolet emission band (approximately 390 nm) and a broad emission band centered at about 527 nm, exhibiting yellow emission color to the naked eyes. When the sample was reduced at the temperatures from 500 to 1050 degrees C, the yellow emission decreased gradually and disappeared completely at 800 degrees C, whereas the ultraviolet emission band became the strongest. Above this temperature, the green emission ( approximately 500 nm) appeared and increased with increasing of reducing temperatures. According to the EPR results and spectral analysis, the yellow and green emissions may arise from the transitions of photogenerated electron close to the conduction band to the deeply trapped hole in the single negatively charged interstitial oxygen ion (Oi(-)) and the single ionized oxygen vacancy (V.O) centers, respectively.

The computational details of a viscoplastic finite element analysis of three-dimensional superplastic forming (SPF) are discussed in this paper. Two typical superplastic forming shapes, conical bulging and rectangle box bulging, were analyzed and the experiment of conical bulging was performed to verify the numerical simulation. The inverse identification of superplastic material parameters incorporating the finite element method and an optimization technique was developed and an activity rule was proposed for effective selection of measurement locations in the experiment. Based on the numerical modeling, the influence of many factors such as the frictional coefficient, strain rate sensitivity and strain rate on the thickness distribution was studied and some useful conclusions were drawn.

An accurate and efficient shell element is presented. The stiffness of the shell element is decomposed into two parts with one part corresponding to stretching and bending deformation and the other part corresponding to shear deformation of the shell. Both parts of the stiffness are calculated with reduced integration rules, thereby improving computational efficiency. Shear strains are averaged on the reference surface such that neither locking phenomena nor any zero energy mode can occur. The satisfactory behaviour of the element is demonstrated in several numerical examples.

In this paper, we describe sex-related health risks among hostesses in two metropolises in China based on data obtained from in-depth interviews. The data show that hostesses, many engaging in commercial sex, are vulnerable to HIV infection, unwanted pregnancies and reproductive tract infections. Nevertheless, many obstacles still are present that hinder them from engaging in safe sex. The findings from our study illustrate the need for targeted interventions in order to improve reproductive health and promote safe sex among this group.

The free vibration problem of unsymmetrical sandwich plates with laminated composite faces and orthotropic core is analysed in the consideration of the effects of bending, transverse shear, plane inertia, rotatory inertia, and coupling inertia. The spline finite point method (SFPM) is selected to solve the present problem and to establish the basic formulae for a computer programme that can be run on microcomputer. A lot of numerical examples of the cross-ply face sandwich plates, with various boundary conditions, are obtained by the present method to make clear for coupling effects of composite material plates and to seek the optimum ply design of engineering structures.

Research on dielectric elastomer generators (DEGs) which can be utilized to convert mechanical energy to electrical energy has gained wide attention lately. However, very few works account for the operating temperature, viscoelasticity and current leakage in the analysis of DEGs simultaneously. In this study, under several compound four-stroke conversion cycles, the electromechanical performance and energy conversion of a dissipative DEG made of a very-high-bond (VHB) elastomer are investigated at different operating temperatures. The performance parameters such as energy density and conversion efficiency are calculated under different temperatures. Moreover, the common failure modes of the generator are considered: material rupture, loss of tension, electrical breakdown and electromechanical instability. The numerical results have distinctly shown that the operating temperature plays an important role in the performance of DEGs, which could possibly make a larger conversion efficiency for the DEG.

In this paper, a neural network (NN) model was designated to identify the geo- metric parameters of drawbead in sheet forming processes. The genetic algorithm (GA) was used to determine the neuron numbers of the hidden layers of the neural network, and a sample design method with the strategy of updating training sam- ples was also used for the convergence. The NN model goes through a progressive retraining process and the numerical study shows that this technique can give a good result of the parameter identification of drawbead.

Delaminations of the embedded passive components are often associated with reliability problems. Understanding the delamination can help us quickly identify the failure cause at an early stage of the failure analysis. In this work, defects of buried capacitors have been detected by use of scanning acoustic microscopy (SAM). The results show that SAM can be a powerful analytical tool for the nondestructive evaluation of delaminations in buried passive components. T-scan is an effective method for determining the existence of the internal defects, and TAMI-scan is shown to be capable of detecting the location and size of the delamination and void.

The frequency selective surfaces (FSS) on both normally and in-plane biased ferrite slab is analyzed using the full-wave moment method solution in this paper. The extra degree of freedom offered by the biased ferrite can be used to tune the resonance characteristics of FSS. Numerical results show that the reflection band center frequencies can be adjusted by several gigahertz.