Sustainability of process improvements: an application of the experiential learning model (ELM)

Despite the pervasiveness of process improvement (Lean or Six Sigma) programmes, there is a rising concern regarding the sustainability of these programmes. Several studies point out that initial operational efficiency gains as a result of these programmes simply disappear over time. Using process improvement implementation experiences in an aircraft manufacturing and distribution operation, we studied long-term sustainability of process improvement events. We found that process owners of successful improvement events applied experiential learning model (ELM). The ELM is a cycle of – (1) concrete experience, (2) reflective observations, and (3) abstract conceptualizations, and (4) active experimentation. This study finds that when the ELM cycle is repeated many times over an extended period to continuously improve, and documented using A3 reports, that the improvement is sustained.     

Design and implementation of low complexity circularly symmetric 2D FIR filter architectures

Multidimensional Systems and Signal Processing - This paper presents a low complexity two dimensional (2D) circular symmetric Finite Impulse Response (FIR) filter design and implementation of...     

Salient objects detection in dynamic scenes using color and texture features

Visual saliency is an important research topic in the field of computer vision due to its numerous possible applications. It helps to focus on regions of interest instead of processing the whole image or video data. Detecting visual saliency in still images has been widely addressed in literature with several formulations. However, visual saliency detection in videos has attracted little attention, and is a more challenging task due to additional temporal information. A common approach for obtaining a spatio-temporal saliency map is to combine a static saliency map and a dynamic saliency map. In our work, we model the dynamic textures in a dynamic scene with local binary patterns to compute the dynamic saliency map, and we use color features to compute the static saliency map. Both saliency maps are computed using a bio-inspired mechanism of human visual system with a discriminant formulation known as center surround saliency, and are fused in a proper way. The proposed model has been extensively evaluated with diverse publicly available datasets which contain several videos of dynamic scenes, and comparison with state-of-the art methods shows that it achieves competitive results.     

Breast cancer diagnosis in an early stage using novel deep learning with hybrid optimization technique

Multimedia Tools and Applications - Breast cancer is one of the primary causes of death that is occurred in females around the world. So, the recognition and categorization of initial phase breast...     

Performance evaluation and implementation of convolution coded OFDM modem in wireless underwater acoustic communication

High‐data transmission rate and reliable communication in underwater acoustic channel is challenging because of limited bandwidth, multipath propagation, and Doppler shift, which results in poor bit error performance. Under this constraint, this paper explains the simulation results of underwater wireless acoustic data transmission system by using quadrature phase shift keying modulation with convolution encoder at the transmitter and proposed Viterbi decoder at the receiver. The decoder algorithm in comparison with MATLAB inbuilt function shows asserting improved results. This paper evaluates the performance of convolution coded orthogonal frequency division multiplexing modem, which is studied over typical underwater channel through an extensive computer simulation and a semirealistic experimentation. The performance of convolution coded orthogonal frequency division multiplexing system is measured in time domain plots, bit error rate curves, and number of bit errors per frame over additive white Gaussian noise and Rayleigh channel conditions.     

Experimental study on laboratory scale Totalized Hydrogen Energy Utilization System using wind power data

The renewable energy source like wind energy generates electric power with intermittent nature. Hydrogen energy system can help to solve the fluctuation problem of the wind power. Totalized Hydrogen Energy Utilization System (THEUS) consists of a Unitized Reversible Fuel Cell (URFC), a hydrogen storage tank, and other auxiliary components. Wind power is inherently variable; the URFC will be subjected to a dynamic input power profile in water electrolyzer mode operation. This paper describes the THEUS operation and performance at different variations in intermittent wind power. The performance of the THEUS was evaluated in water electrolyzer and fuel cell mode operation. The stack efficiency, system efficiency, and system efficiency including heat output from the URFC were presented at each operation. The total efficiency of the URFC and THEUS were also investigated. The maximum total efficiency of the URFC and THEUS were 53% and 66%, respectively.     

Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.     

The Global Nonlinear Galerkin Method for the Analysis of Elastic Large Deflections of Plates under Combined Loads: A Scalar Homotopy Method for the Direct Solution of Nonlinear Algebraic Equations

In this paper, the global nonlinear Galerkin method is used to perform an accurate and efficient analysis of the large deflection behavior of a simply-supported rectangular plate under combined loads. Through applying the Galerkin method to the governing nonlinear partial differential equations (PDEs) of the plate, we derive a system of coupled third order nonlinear algebraic equations (NAEs). However, the resultant system of NAEs is thought to be hard to tackle because one has to find the one physical solution from among the possible multiple solutions. Therefore, a suitable initial guess is required to lead to the real solution for given load conditions. The feature of this paper is that we apply the global nonlinear Galerkin method to the governing PDEs and solve the resultant NAEs directly in each load step. To keep track of the physical solution, the initial guess for the current load step is provided by taking the solution of the NAEs for the last step as the initial guess. Besides, the size of the NAEs grows dramatically larger, with the increase of the number of terms of the trial functions, which will cost much more computational efforts. An exponentially convergent scalar homotopy algorithm (ECSHA) is introduced to solve the large set of NAEs. The approach in the present paper is more direct and simpler than either the incremental global Galerkin method, or the incremental local Galerkin method (finite element method) based on a symmetric incremental weak-form; both of which methods lead to the inversion of tangent stiffness matrices and Newton-Raphson iterations in each load step. The present method of exponentially convergent scalar homotopy of directly solving the NAEs is much better than the quadratically convergent Newton-Raphson method. Several numerical examples are provided to validate the feasibility and efficiency of the proposed scheme.     

A Simple Locking-Alleviated 3D 8-Node Mixed-Collocation C0 Finite Element with Over-Integration,for Functionally-Graded and Laminated Thick-Section Plates and Shells,with & without Z-Pins

Following previous work of [Dong, El-Gizawy, Juhany, Atluri (2014)], a simple locking-alleviated 3D 8-node mixed-collocation C0 finite element (denoted as CEH8) is developed in this study, for the modeling of functionally-graded or laminated thick-section composite plates and shells, without using higher-order or layer-wise zig-zag plate and shell theories which are widely popularized in the current literature. The present C0 element independently assumes an 18-parameter linearly-varying Cartesian strain field. The independently assumed Cartesian strains are related to the Cartesian strains derived from mesh-based Cartesian displacement interpolations, by exactly enforcing 18 pre-defined constraints at 18 pre-selected collocation points. The constraints are rationally defined to capture the basic kinematics of the 3D 8-node C0 element, and to accurately model each basic deformation mode of tension, bending, shear, and torsion. A 2x2x2 Gauss quadrature is sufficient for evaluating the stiffness matrix of CEH8 C0 3D elements for homogeneous materials, but over-integration (with a higher-order Gauss Quadrature, a layer-wise Gauss Quadrature, or a simple Trapezoidal Rule in the thickness direction) is used for functionally-graded materials or thick-section laminated composite structures with an arbitrary number of laminae. Through several numerical examples, it is clearly shown that the present CEH8 3D C0 element can accurately capture the stress distribution of FG and thick laminated structures with an arbitrary number of laminae even when only one element is used in the thickness direction. In stark contrast to the higher-order or layer-wise zig-zag plate and shell theories, with assumptions for displacement or stress fields in the thickness direction, which may require complicated C1 finite element, the present C0 element can accurately compute the jumps in bending stresses at the interfaces of layers, while the out-of plane normal and shear stresses can be accurately recovered by exploring the equilibrium equations of 3D linear elasticity. By adding the contributing stiffness of z-pins into the stiffness matrix of CEH8, it is also demonstrated that the presently developed method can be used to study the effect of using z-pin reinforcements to reduce the inter-laminar stresses of composite structures, in a very simple and computationally-efficient manner.     

SGBEM Voronoi Cells (SVCs), with Embedded Arbitrary-Shaped Inclusions,Voids, and/or Cracks,for Micromechanical Modeling of Heterogeneous Materials

In this study, SGBEM Voronoi Cells (SVCs), with each cell representing a grain of the material at the micro-level, are developed for direct micromechanical numerical modeling of heterogeneous composites. Each SVC can consist of either a (each with a different) homogenous isotropic matrix, and can include micro-inhomogeneities such as inclusions, voids of a different material, and cracks. These inclusions and voids in each SVC can be arbitrarily-shaped, such as circular, elliptical, polygonal, etc., for 2D problems. Further, the cracks in each SVC can be fully-embedded, edge, branching, or intersecting types, with arbitrary curved shapes. By rearranging the weakly-singular boundary integral equations, a stiffness matrix and a force vector are developed for each SVC with inclusions, voids, and micro-cracks. The stiffness matrix of each SVC is symmetric, positive semidefinite, and has the correct number of rigid-body modes. The stiffness matrix of each SVC and the force vector can also be interpreted to have the same physical meaning as in traditional displacement finite elements, and related to strain energy and the work done. Therefore, the direct coupling of different SVCs (each with a different isotropic material property, and each with heterogeneities of a different material), or the coupling of SVCs with other traditional or special elements, can be achieved by the usual assembly procedure. Moreover, because the heterogeneous micro-structures are modeled directly in the most natural way, as in the present work, by using an SVC to model each grain, one not only saves the labor of meshing and re-meshing, but also reduces the computational burden by several orders of magnitude as compared to the usual FEM. Through several numerical examples, we demonstrate that the SVCs are useful in not only estimating the overall stiffness properties of heterogeneous composite materials, but they are most useful in capturing the local stress concentrations and singularities in each grain, which act as damage precursors, efficiently. Several examples of interaction of cracks with inclusions and voids within each SVC (or material grain) are also presented. Accurate results are obtained for stress intensity factors. Non-collinear fatigue growth of micro-cracks in heterogeneous materialis also modeled very efficiently, with these SVCs, without a need for the complicated re-meshing as is common when using the traditional displacement-based finite element methods.