The Interpretation of Train Rolling Resistance from Fundamental Mechanics

Past efforts in railway improvement have focused on increased train stability and ride quality for safe and smooth operations at higher speed. The question of energy consumption has rarely been considered. In view of projections of higher fuel costs and increased rail traffic volume, energy effects caused by improved train resistance should be considered. First-order expressions for the rolling resistance of freight trains on level tangent track were derived from the basic principles of physics and engineering. The average power dissipated by the suspension system was obtained from a linear model of the track train system. Hysteresis in the soil is computed using basic principles of soil mechanics. Losses due to wheel rolling friction, imposed wheel sliding, and bearings were estimated from simple engineering and considerations. Rolling resistance as would be measured in coast down or drawbar pull tests on level tangent track is found to depend strongly on the quality of the track as well as weight and speed. On good track, most of the rolling resistance is due to bearing resistance, while on poor track, suspension losses predominate. Empirical expressions such as the Davis formula, which have been used in the past by the railroad industry, are unable to describe train rolling resistance adequately because of the way in which they are parameterized. Some of the parameter values obtained from fits to experimental data do not carry the physical meaning with which they were traditionally associated.     

Adaptive spatiotemporal receptive field estimation in the visual pathway

The encoding properties of the visual pathway are under constant control from mechanisms of adaptation and systems-level plasticity. In all but the most artificial experimental conditions, these mechanisms serve to continuously modulate the spatial and temporal receptive field (RF) dynamics. Conventional reverse-correlation techniques designed to capture spatiotemporal RF properties assume invariant stimulus-response relationships over experimental trials and are thus limited in their applicability to more natural experimental conditions. Presented here is an approach to tracking time-varying encoding dynamics in the early visual pathway based on adaptive estimation of the spatiotemporal RF in the time domain. Simulations and experimental data from the lateral geniculate nucleus reveal that subtle features of encoding properties can be captured by the adaptive approach that would otherwise be undetected. Capturing the role of dynamically varying encoding mechanisms is vital to our understanding of vision on the natural setting, where there is absence of a true steady state.     

Spatially adaptive techniques for level set methods and incompressible flow

Since the seminal work of [Sussman, M, Smereka P, Osher S. A level set approach for computing solutions to incompressible two-phase flow. J Comput Phys 1994;114:146–59] on coupling the level set method of [Osher S, Sethian J. Fronts propagating with curvature-dependent speed: algorithms based on Hamilton–Jacobi formulations. J Comput Phys 1988;79:12–49] to the equations for two-phase incompressible flow, there has been a great deal of interest in this area. That work demonstrated the most powerful aspects of the level set method, i.e. automatic handling of topological changes such as merging and pinching, as well as robust geometric information such as normals and curvature. Interestingly, this work also demonstrated the largest weakness of the level set method, i.e. mass or information loss characteristic of most Eulerian capturing techniques. In fact, [Sussman M, Smereka P, Osher S. A level set approach for computing solutions to incompressible two-phase flow. J Comput Phys 1994;114:146–59] introduced a partial differential equation for battling this weakness, without which their work would not have been possible. In this paper, we discuss both historical and most recent works focused on improving the computational accuracy of the level set method focusing in part on applications related to incompressible flow due to both of its popularity and stringent accuracy requirements. Thus, we discuss higher order accurate numerical methods such as Hamilton–Jacobi WENO [Jiang G-S, Peng D. Weighted ENO schemes for Hamilton–Jacobi equations. SIAM J Sci Comput 2000;21:2126–43], methods for maintaining a signed distance function, hybrid methods such as the particle level set method [Enright D, Fedkiw R, Ferziger J, Mitchell I. A hybrid particle level set method for improved interface capturing. J Comput Phys 2002;183:83–116] and the coupled level set volume of fluid method [Sussman M, Puckett EG. A coupled level set and volume-of-fluid method for computing 3d and axisymmetric incompressible two-phase flows. J Comput Phys 2000;162:301–37], and adaptive gridding techniques such as the octree approach to free surface flows proposed in [Losasso F, Gibou F, Fedkiw R. Simulating water and smoke with an octree data structure, ACM Trans Graph (SIGGRAPH Proc) 2004;23:457–62].     

The Implementation of Innovation by a Multinational Operating in Two Different Environments: A Comparative Study

The aim of the paper is to examine the innovation initiatives and processes followed by two subsidiaries of a German multinational company operating in Europe and Asia and to compare the innovativeness of their operations in these two locations. The study examined the innovation processes followed by the two subsidiary firms operating in Germany and Malaysia, the actual problems faced by them, the critical success factors involved in the implementation, and the work climates of the firms. Interestingly, it was found that both firms followed similar innovation processes. Nevertheless, different types of problems and critical success factors were applicable to both firms. The results showed that the Malaysian subsidiary faced more behavioural problems while the German subsidiary encountered more technical problems. Further, the study showed that a lack of knowledge was the common problem faced equally by both firms. The study demonstrated that the German subsidiary had better working climate compared to its counterpart in Malaysia. Finally, the German subsidiary was found to be more innovation–active than the Malaysian subsidiary as it introduced more types of innovation, interacted with more types of entity in the external environment and introduced more types of training.     

Hydrodynamics of asymmetrical film thinning

The thinning of the film beneath a liquid drop is often faster than predicted by radial drainage. This could be explained by asymmetrical drainage, but mathematical difficulties are then encountered. However, analytical solutions may be obtained for the two-dimensional case and expressions are derived here for the asymmetric viscous drainage of films trapped between convex and concave wedges. Solutions for the symmetrical drainage beneath wedges and parabolae are also presented which are analogous to the three-dimensional drainage beneath cones and paraboloids previously derived.     

Informed consent: how much information is enough?

BACKGROUND: Recent judicial decisions involving informed consent have led to some medical practitioners altering the way they obtain consent. The aim of this study was to determine the degree to which patients understood the risks associated with a surgical procedure after giving routine consent and whether providing additional detailed verbal and/or written information improved their understanding. It was further determined whether the provision of more extensive information altered patients' anxiety levels. METHODS: Patients undergoing femoral popliteal bypass or carotid surgery were randomized to obtain either routine consent only or routine consent with verbal or written or verbal and written consent. Patients undertook a pre-operative risk and complication questionnaire, a pre- and postoperative anxiety and depression evaluation and a follow-up questionnaire 6 weeks after discharge. RESULTS: Thirty-two patients were included in the trial. The comprehension questionnaire resulted in a correct percentage response of 48% for the routine information only, 59% with added verbal information, 59% with added written information and 55% with added written and verbal information. Twenty-five per cent of patients stated that they had a poor understanding of the risks and complications of the procedure. CONCLUSIONS: Additional written or verbal information did not improve a patient's understanding of risks and complications of the procedure. It also did not improve patients' perceived understanding of the operation or its complications. Patients' anxiety levels were unaltered by the increase in the information they were given. The information provided to patients should be simple, easy to understand and list any possible major complications to enable the patient to determine whether to undergo or decline a procedure.     

What does a man want?

Discusses the changing roles and expectations held of men in modern society and the confusion this has engendered, a confusion that at times may be linked with resulting domestic and societal problems. The author discusses the emergence of the men's movement and the quest for a clearer masculine identity and a greater connection and communication between men. Also treated is the inability of many men to engage in intimacy. Psychology has provided some healing techniques to bridge the gap between men and women (e.g., sensitivity training for men and assertiveness training for women), but the author cites the need for training in good manners, decency, and good will. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solids flow between interconnected shallow fluidized beds

Many industrial processes utilising two or more fluidized beds are connected such that one bed flows through an opening into the other. By operating regions of the two beds at different superficial gas velocities, a bulk density difference can be created between them to effect a solids transfer through a submerged opening. The resultant flow of solids between fluidized beds of sand (194 μm and 224 μm) is modelled on the basis of a liquid analogy and force-momentum balances. The correct functional dependency of the solids flow rate is predicted for a range of gas velocities; experimental results are 70–90% of the predicted values. The prediction of the solids flow rate for changes in the size of the openings between the beds is less satisfactory, possibly because of the return flow of solids which is associated with the forward flow.