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Paper investigates the use of newly defined numerical method based on weak-link theory in the context of insulating liquid AC breakdown withstand improvement using impregnated paper coating of the electrodes. It is shown how liquid-impregnated paper differently affects breakdown withstand depending on field non-uniformity. Based on these findings, guidelines for breakdown withstand improvement are presented.

Underground low voltage cables as well as medium voltage ones (AC and DC) still present insulations made of special paper. The most important issue of this simple and efficient material is ageing, especially under stress conditions. This research tries to establish a mathematical model (based on computer implemented numerical methods) which can easily characterize the ageing process of the dielectric material even under cyclic voltage stress, in case of DC low voltage cables. Focused on the evaluation of the threshold value of charge accumulation by use of parameters derived from PEA measurements, the article investigates the space charge evolution under cyclic stress of papers for DC cables applications.

We highlight some problems in this paper. They lead to question the model itself.

Demands for small-scale and low-cost robots have witnessed a great increase in recent years [1–5]. This paper introduces the design and fabrication of a novel, simple, low-cost and designer-friendly locomotive robot. The materials and tools to build the robot originate from everyday life. The robot is pneumatically powered and manually controlled by simply pumping and vacuuming the syringe repeatedly, which realizes reliable locomotion by folding and opening of the planes. In order to realize this complicated motion, a “3D Sticky Actuator” is developed. The motion and force analysis of actuator are then modelled by the numerical method to develop the relations between design parameters. This suggests a systematic and user interactive way of manufacturing various shapes of the actuator, depending on user-defined road condition (e.g. obstacles and slopes) and other constraints. One key advantage of the paper-based robot is suggested by its high feasibility.

We complete a gap in the proof that exceptional polynomials are complete orthogonal systems in the associated Hilbert spaces.

A numerical method is presented for the computation of spacing error bounds in vehicle platoons. The resulted bounds can be applied to evaluate performance of specific platoon control algorithms. The upper bound calculation is based on the computation of worst-case induced L 2 -gains of systems defined between the disturbance inputs to the leader vehicle and the spacing errors of the follower vehicles. The worst-case is defined subject to heterogeneity in the vehicle dynamics. The method is applicable both in the frequency- and the time-domain. The latter enables the extension of robustness analysis to a wider class of uncertainties and communication topologies. The method is illustrated on a numerical example with leader and predecessor following control architecture.

In this work, numerical analysis of nonlinear ferromagnetic problems is presented using the three-dimensional time-domain flnite element method (TDFEM). Formulated with the second- order nonlinear partial difierential equation (PDE) combined with the inverse Jiles-Atherton (J-A) vector hysteresis model, the nonlinear problems are solved in the time domain with the Newton- Raphson method. To solve the ordinary difierential equation (ODE) representing the magnetic hysteresis accurately and e-ciently, several ODE solvers are speciflcally designed and investigated. To improve the computational e-ciency of the Newton-Raphson method, the multi-dimensional secant methods, aka Broyden's methods, are incorporated in the nonlinear TDFEM solver. A nonuniform time-stepping scheme is also developed using the weighted residual approach to remove the requirement of a uniform time-step size during the simulation. The capability and the performance of the proposed methods are demonstrated by various numerical examples.

Computation of the stability limit of systems with time delay is essential in many research and industrial applications. Most of the computational methods consider the exact model of the system, and do not take into account the uncertainties. However, the stability charts are highly sensitive to the change of input parameters, such as eigenfrequency and timedelay. A method has been developed to determine the robust stability limits of delayed dynamical systems, which is insensitive to the parameter fluctuations of the dynamic system. The method is combined with an eficient numerical method, the so-called Multi-Dimensional Bisection Method and the resultant robust stability limits are compared by analytical results.

The development of mathematical models that describe industrial processes is playing an increasing role in industrial context, because such models can replace, in some cases, experimental simulation, in a more inexpensive and flexible way. In this paper is presented a preliminary study of a transient model of a continuous moving bed reactor - the digester - used in the pulp and paper industry. In this complex and heterogeneous digester a moving bed of wood chips, containing cellulose, hemicellulose and lignin, reacts with sodium hydroxide and sodium sulfide - dissolved in a liquid phase - to remove the lignin from the cellulose fibers. The mathematical model studied here has been developed by Fernandes in a forthcoming Ph.D Thesis. The model is derived from the fundamental principles of mass and energy balance and is represented by a system of 15 partial differential equations (PDE) of convection-reaction type. The numerical methods used in the discretization of this PDE system are based on operator splitting which essentially consists in considering separately convection and reaction phenomena. This approach allows the use of methods with different properties - explicitness, implicitness and order - for each subprocess. The final global class of methods represents in some sense a “patching of tailored methods” well adapted to the feature of individual phenomena. Numerical simulations of the concentrations of organics and inorganics are presented.

In this paper, backpropagation networks are used to predict basis weight and moisture content in the pulp machine, Kappa number in the digester, and brightness in the bleaching plant. Historical data from these processes in Weyerhaeuser Canada is analyzed to develop an empirical predictive model for process variables and to gain a better understanding of the dependence of qualities on these variables. In order to avoid deficiencies associated in generalized descent method for training the network, the conjugate gradient method has been used. >

[synopsis] This paper is a research development about the design of atomization nozzles that manufacture the minute metal powder used in an industrial field. The purpose of study is to clarify the influence of exit shape of an annular nozzle on the flow fields of an annular supersonic jet. This paper has clarified a gas-liquid two-phase flow issued from an annular nozzle to research and develop a practicable nozzle. Especially, the gas-liquid two-phase flows for the air-molten aluminum have been clarified by the numerical analysis. Finally, the velocity, pressure contours, and the FVF of the flow on the effects of an annular supersonic jet on the minute powder of the air-water or air-molten aluminum are examined. As a result, it is clarified that the flow fields of a gas-liquid two-phase flow of the nozzle exit are influenced considerably by the configuration of molten metal nozzle exit and the stagnation pressure. Moreover, the fluid volume fraction (FVF) of the molten aluminum is examined, and according the breakup mechanism of minute aluminum powder is clarified.

In this paper, we focus on the proposed algorithms to solve a linear programming problem with the convex combination of the max–min and the max–average composition and the max–star composition, respectively. They have been proposed by Ghodousian and Khorram [A. Ghodousian, E. Khorram, Solving a linear programming problem with the convex combination of the max–min and the max–average fuzzy relation equations, Appl. Math. Comput. 180 (2006) 411–418] and Khorram et al. [E. Khorram, A. Ghodousian, A. Abbasi Molai, Solving linear optimization problems with max–star composition equation constraints, Appl. Math. Comput. 179 (2006) 654–661], respectively. Firstly, we show that the “Tabular method algorithm” in the first paper and the “First procedure” in the second paper may not lead to the optimal solutions of the two models in some cases. Secondly, we generalize the proposed algorithm by Abbasi Molai and Khorram [A. Abbasi Molai, E. Khorram, A modified algorithm for solving the proposed models by Ghodousian and Khorram and Khorram and Ghodousian, Appl. Math. Comput. 190 (2007) 1161–1167] to solve the two models. In fact, it modifies the presented algorithms in the two papers. Finally, some numerical examples are given to illustrate the purposes.

Comment on the paper “A class of methods based on non-polynomial spline functions for the solution of a special fourth-order boundary-value problems with engineering applications” in Applied Mathematics and Computation 174 (2006) 1169–1180. The paper considered a class of two-point boundary-value problems of the form (1) d 4 y d x 4 + f ( x ) y = g ( x ) , a ⩽ x ⩽ b , (2) y ( a ) = A 1 , y ( b ) = A 2 , y ′ ( a ) = B 1 , y ′ ( b ) = B 2 , where f ( x ) and g ( x ) are continuous on [ a , b ], and A i and B i ( i = 1, 2) are finite real constants. Here we correct some mistake in derivation of non-polynomial spline, boundary formulas, truncation errors, convergence analysis and computational experiments.

This issue of Computing contains the revised and extended versions of a selection of the best papers from the 10th International Conference on Mobile Web Information Systems,MobiWIS 2013, held in Paphos, Cyprus, inAugust 2013.MobiWIS proposes itself as the premier venue to present and discuss all aspects related to issues and solutions of mobile technologies when it comes to the engineering of mobile and web-based information systems. The topics covered by the conference were Mobile Web and Social Applications,Middleware/SOA,MobileWeb Searching, Contextand Location-Aware Services, DataManagement, Mobile Cloud Services,Mobile Internet of Things, Mobile Web Security, Trust and Privacy, Mobile Networks, Protocols and Applications,MobileCommerce andBusiness Services,HCI. Thewide range of topics shows that the field is complex and dynamic and that it is called to respond to the new challenges posed by a rapid evolution of use and technology. The best papers of MobiWIS 2013 were selected by the MobiWIS PC chairs based on their quality. Their authorswere invited to submit revised and significantly extended versions. All invited papers were reviewed again by selected members of the Program Committee of the conference and checked for quality.