Real-time optimization of plug-in hybrid electric vehicles based on Pontryagin’s minimum principle

Clean Technologies and Environmental Policy - Battery aging can greatly reduce the energy efficiency of plug-in hybrid electric vehicles (PHEVs). This paper presents a novel real-time energy...     

Jacobi’s bound for independent systems of algebraic partial differential equations

In this paper we prove Jacobi’s bound for systems of n partial differential polynomials in n differential variables, which are independent over a prime differential ideal mathfrakp{mathfrak{p}} . This generalizes on the one hand our result (Kondratieva et al. in On Jacobi’s bound for systems of differential polynomials, algebra. Moscow University Press, Moscow, pp 79–85, 1982) about Jacobi’s bound for ordinary differential polynomials independent over a prime differential ideal mathfrakp{mathfrak{p}} and, on the other hand, the result by Tomasovic (A generalized Jacobi conjecture for arbitrary systems of algebraic differential equations. PhD thesis, Columbia University, 1976), who proposed a version of Jacobi’s bound for partial differential polynomials and proved it in the linear case. In Kondratieva et al. (Differential and difference dimension polynomials, Kluwer, Dordrecht, 1999) we gave another proof of this result by Tomasovic. The exposition in the present paper follows our proof in Kondratieva et al. (Differential and difference dimension polynomials, Kluwer, Dordrecht, pp 273–280, 1999).     

An algorithm for the complete symmetry classification of differential equations based on Wu’s method

In this paper, an alternative algorithm which uses Wu’s method (differential characteristic set algorithm) for the complete symmetry classification of (partial) differential equations containing arbitrary parameter is proposed. The classification is determined by decomposing the solution set of determining equations into a union of a series of zero sets of differential characteristic sets of the corresponding differential polynomial system of the determining equations. Each branch of the decomposition yields a class of symmetries and associated parameters. The algorithm makes the classification become direct and systematic. This is also a new application of Wu’s method in the field of differential equations. As illustrative examples of our algorithm, the complete potential symmetry classifications of linear and nonlinear wave equations with an arbitrary function parameter and both classical and nonclassical symmetries of a parametric Burgers equation are presented.     

Study of the load-separation principle and a procedure to estimate ηp-factor for structures with different geometries

The theoretical background of load separation principle has been reviewed. Based on dimensional analysis, experimental results and finite element analysis the conditions for the validity of this principle have been studied and a method has been suggested to estimate the load separation function, and hence to estimate the _p-factor and to determine the J-R resistance curve easily from records of a single specimen or structure.     

The role of navigation instruction at intersections for older drivers and those with early Alzheimer’s disease

AimsOur purpose was to explore the effect of navigation instruction on older drivers’ driving performance at left turn intersections. Left turns at intersections are particularly complex because they require many perceptive and cognitive abilities under considerable time pressure.MethodsFifty-four participants were recruited: 18 drivers with early-stage Alzheimer’s disease (AD), 18 neurologically healthy older drivers and 18 younger individuals. Various cognitive processes were measured, and 9 left turn maneuvers with or without navigation instruction were evaluated during an in-traffic road test. The psychomotor, planning and decision-making components involved in left turn were also analyzed closely.ResultsOnly older drivers (both healthy drivers and those with AD) were negatively affected by navigation instruction during the maneuver. The planning and decision-making components were more likely to be affected by the navigation instruction.ConclusionThis finding highlights the importance of carefully considering the use of navigation instructions when developing navigation systems. Adapting this instruction is necessary to simplify our understanding of the real-world driving environment and to avoid increasing the cognitive load of older drivers.     

Mandel and Cryer problems of fluid-saturated foams with negative Poisson’s ratio

Summary. Professor Lakes created foams with negative Poissons ratios in 1987. Since then he has examined interesting and fantastic characteristics of such foams and proposed their realistic and future possible applications. The present study was motivated by our interest in how such a foam behaves for a sudden loading if it is saturated with fluid. To highlight mechanical interactions between elastic deformation of such a foam and diffusion of the saturating fluid, we solved four problems in a unified manner: 2D and 3D, Cryer and Mandel problems. It is found that for all these problems the pore fluid pressure near the sample center climbs up from its initial pressure and then declines and vanishes; its peak is much higher for negative Poissons ratios, that is, much more remarkable Mandel-Cryer effect. Stress components such as tangential stress also show similar behavior, and the tangential stress has tension near the sample surface in spite of compressive loading. It is also found that for the step-like axial compression the Mandel cylinder sample laterally expands immediately after the loading, then shrinks and finally becomes thinner than its original thickness; a possible application is proposed.     

Combining Maxwell’s methodology with the BEM for evaluating the two-dimensional effective properties of composite and micro-cracked materials

Maxwell’s methodology is combined with the boundary element method (BEM) for evaluating the two-dimensional effective elastic properties of composite, porous, and microcracked isotropic materials with periodic or random structure. The approach is based on the idea that the effective properties of the material can be deduced from the effects that a cluster of fibers, pores, or cracks embedded in an infinite matrix has on the far-fields. The fibers, pores, or cracks can have arbitrary shapes, sizes, and elastic properties, provided that the overall behavior is isotropic, and their effects are assumed to be the same as those of an equivalent circular inhomogeneity. The key aspect of the approach is to precisely account for the interactions between all the constituents in the cluster that represent the material in question. This is done by using the complex-variables version of the BEM to solve the problem of a finite cluster of fibers, pores or cracks embedded an infinite isotropic, linearly elastic matrix. The effective properties of the material are evaluated by comparing the far-field solutions for the cluster with that of the equivalent inhomogeneity. It is shown that the model adequately captures the influence of the micro-structure of the material on its overall properties.     

Melnikov’s method for controlled stochastic oscillations of a rocking block with fractional derivative

The problem of controlling a rocking block with fractional dissipation so as to prevent it from leaving a prescribed set of bounded oscillations has a number of interesting applications in many scientific and technological fields. This work develops an analytical framework to describe the influence of control on the behavior of a fractionally dissipative rocking block subject to random acceleration of the ground. Control equations are developed and control strategies leading to optimal suppression of instability are asymptotically described under the assumptions of weak dissipation along with a small energy noise. Under these assumptions, the behavior of the block is interpreted as weakly perturbed rocking oscillations close to a generic periodic solution, and the Melnikov approximations are considered as the necessary conditions of instability. The stochastic Melnikov criterion derived in this paper allows for an approximate calculation of an upper bound to the overturning probability as well as to the representation of an optimal control strategy. The Melnikov criterion for stochastic rocking oscillations in the presence of convenient control strategies are derived explicitly for the first time, using an extension of the Melnikov theory to a model with fractional derivative.     

Definition of diagonal Poisson’s ratio and elastic modulus for infill masonry walls

The prediction of the response of infilled frames through the simplified approach of substituting the infill with an equivalent pin-jointed strut is treated. In this framework the results of an experimental study for the mechanical characterization of different types of masonry infills having the aim of estimating strength, Young modulus and Poisson’s ratio are presented. Four types of masonry were investigated and subjected to ordinary compressive tests orthogonally to the mortar beds and along the directions of the mortar beds. The experimental campaign confirmed the possibility of using an orthotropic plate model for prediction of the Poisson’s ratio and Young modulus along the diagonal direction of infills (these parameters are requested by a model already known in the literature for the identification of struts equivalent to masonry infills). The experimental campaign made it possible to recognise a correlation between the Poisson’s ratios and the strengths of masonries investigated along the orthotropic axes and to obtain the diagonal Poisson’s ratio without specific experimental tests. Finally, the experimental responses of some infilled frames were used to test the reliability of the model proposed here.     

Quantification and integration of Kano’s model into QFD for optimising product design

With increasing concerns on customer needs in today’s competitive market, the issue of incorporating customer requirements into product design arises the interest of both researchers and practitioners. Quality Function Deployment (QFD) is a well-known methodology for customer-driven product design. However, conventionally, QFD analysis has a major challenge in understanding customer needs accurately. Kano’s model, which studies the nature of customer needs, provides a way for a better classification of customer needs. However, seldom research contributions are found in terms of integrating Kano’s model with QFD quantitatively. In this research, a novel integration approach is proposed. At first, Kano’s model is quantified by identifying relationship between customer needs and customer satisfaction (CS). Next, both qualitative and quantitative results from Kano’s model are integrated into QFD. Finally, a mixed non-linear integer programming model is formulated to maximise CS under cost and technical constraints. In this research, an illustrative example associated with the design of notebook computers is also presented to demonstrate the availability of the proposed approach.     

A Comparison of DHW Algorithm for Temperature Distribution Calculation with Fourier’s Algorithm for Transmission of Heat between Discrete Bodies

In this article, our damped-heat wave (DHW) algorithm for the calculation of temperature distribution in a homogeneous finite medium is compared with Fourier’s algorithm for transmission of heat between discrete bodies.     

A path-following driver model with longitudinal and lateral control of vehicle’s motion

The use of closed-loop driver models is important for accurate vehicle simulations and in active safety systems evaluation. In this paper we present a combined longitudinal-lateral controller that is regulating the steering angle and throttle/brake levels by previewing the path ahead of the vehicle. The lateral steering controller is using, as input, the heading and position deviation between the vehicle and the road. The controller is using fixed gains with a simple gain scheduling based on the vehicle’s speed. The longitudinal speed controller is using the curvature of the path ahead of the vehicle to determine the appropriate velocity of the vehicle. The longitudinal-lateral controller is tested by driving a double-lane change (ISO 3888-2) and a lap around a racing track.     

A new method for the measurement of static and dynamic Young’s moduli of long fibres

This article describes a new laser systems to measure the Young’s modulus of a long fibre based on the diffraction of light. Two setups are presented. The first setup has been used to measure the static Young’s modulus of a thin basalt fibre (10 μm diameter, 93 mm length). The second setup called “impulse mechanical spectrometer” was used to measure the dynamic Young’s modulus of a long polyamide fibre (128 μm diameter, 371 mm length). A change of the vibration frequency is achieved by changing the length of the fibre or the load. The damping coefficient was also estimated in the dynamic characterisation. The presented experimental method does not require calibration.     

Prediction of Young’s modulus and Poisson ratio for foamed metals using octahedron model

Abstract

The present paper deals with the mathematical–physical expression of Young’s modulus and Poisson ratio of foamed metals. As it is known that, Young’s modulus and Poisson ratio are two basic mechanical parameters of engineering materials. Foamed metal is a class of excellent engineering materials with dual attributes of structural and functional characteristics; therefore, these two parameters are investigated for these materials, and the relevant mathematical–physical expressions are derived from the ‘octahedron model’ of porous materials in the present paper. The results show that the apparent Young’s modulus displays a quite complicated mathematical relationship to porosity of the porous body, and the apparent Poisson ratio is just a characteristic of the material constant almost not relative to porosity of the foamed metal.     

Pore space analysis of cement-based materials by combined Nitrogen sorption – Wood’s metal impregnation and multi-cycle mercury intrusion

The analysis of pore space is crucial for a profound understanding of transport and mechanical properties of porous materials. Cement-based materials have a broad pore size distribution ranging from micro- to macro-pores. The analysis of this kind of pore space therefore becomes difficult. Because the resolution of image based methods is limited, indirect analysis methods like Nitrogen sorption or mercury intrusion porosimetry (MIP) are often applied. The standard MIP results in an underestimation of large pores because of its intrinsic limitation due to ink-bottle type pores (i.e., pores that are connected to the surface by smaller neck entrances only). The adsorption of Nitrogen seems to be less influenced by such connectivity effects, but the analysis of pores larger than about 100 nm is not possible.To overcome these limitations, in this study pores were selectively filled with Wood’s metal. The liquid metal (at elevated temperature) is intruded into the samples by applying different pressure regimes and then re-solidified in place. The partial impregnation with this metal allowed the analysis of non-ink-bottle type pore space in a subsequent Nitrogen sorption experiment and its comparison with an empty pore system. Furthermore, Mercury intrusion experiments with an additional pressurization–depressurization cycles (multi-cycle-MIP) were performed. The pore size distributions and pore volumes as calculated from Nitrogen sorption data are then compared with MIP and multi-cycle MIP data.     

Gender bias and explanation models for the phenomenon of women’s discriminations in research careers

In the present paper four myths of gender differences in scientific performance are presented and discussed. The persistence of these myths in different forms of evaluation is influencing the women’s discriminations in research careers in combination with effects explained in other explanation models for the existence of the unseen barrier (glass ceiling) that keeps women from rising to the upper levels of the corporate ladder.