Constant velocity water entry is important in understanding planing and slamming of marine vessels. A test rig has been developed that drives a wedge section with end plates down guides to enter the water vertically at near constant velocity. Entry force and velocity are measured. Analysis of the test data shows that the wetting factor is about 1.6 at low deadrise angles and reduces nearly linearly to 1.3 at 451 deadrise angle. The added mass increases quadratically with immersed depth until the chines become wetted. It then continues to increase at a reducing rate, reaching a maximum value between 20% and 80% greater than at chine immersion. The flow momentum drag coefficient is estimated from the results to be 0.78 at 51 deadrise angle reducing to 0.41 at 451 deadrise angles. Constant velocity exit tests show that the momentum of the added mass is expended in driving the water above the surface level and that exit forces are low and equivalent to a drag coefficient of about 1.0-1.3. Considerable dynamic noise limits the accuracy of the results, particularly after chine immersion

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The paper stems from an assessment of the suitability of bond graphs for modelling mechanical systems. Although mathematically rigorous, difficulties arise with intuitive interpretation of bond graphs. The source of the difficulty is the semantics commonly adopted and the way that they relate to traditional interpretations of mechanical system dynamics. Bond graphs represent dynamic systems as energy manipulators with the flow of energy given by the product of two power variables, commonly described as the flow and effort variables. In the mechanical domain, velocity is commonly described as the flow variable, and force as the effort variable. The physical interpretation of mechanical systems and the analogies across systems domains are much improved if force is adopted as the flow variable and the second power variable (i.e. velocity) is called the potential variable. Force can be represented as the flow of a mechanical charge, where the total charge stored in a mass is equal to its momentum. It displays all the properties of a flow variable. Mass is then analogous to electrical capacitance, and mechanical compliance is analogous to electrical inductance.

Many companies still do not achieve the success rates they desire with new product introductions to the market. A method has been developed to aid companies to self-evaluate their product development processes. The method meets an identified need for a nonprescriptive procedure to evaluate an existing or proposed product development process at a detailed level, both in the context of the company's own products, processes, procedures and markets, and in the context of accepted good practice.The specification and development of the process and facilities needed for the manufacture of a product are identified as fundamental generic issues within the product development process that must be handled effectively to achieve successful product outcomes. The paper describes the main constructs of the evaluation method in relation to manufacturing issues, and presents results and findings from trials conducted in industry. It is seen that great care is needed to ensure that company practitioners make objective assessments of the important factors. Further work is planned to develop the method as an interactive computer tool and to conduct more trials.

The aim of the work reported here was to investigate the potential benefits of rear suspension systems for mountain bikes and to develop numerical models that could be used in future to help with the design of improved suspension configurations. As the basis for a study of the effect of rear suspensions, two bicycles were chosen: one with full suspension and one with only front suspension (hard tail). Apart from the rear suspension, all other aspects of the bicycles were closely matched. In order to control the number of variables, a special rolling road test rig was used. Eight subjects were asked to ride each bicycle on the rig in random order. Measurements were taken of pedal torque and speed, rear wheel speed, forward thrust at front axle and vertical acceleration at the saddle and handlebars. Physiological measurements were also taken, but these are reported elsewhere. A DADS model of the rolling road rig, bicycle and rider was created and numerical simulations were performed. The results of the numerical simulations compared well with the experimental results. Unmeasured parameters predicted by the DADS model could therefore be used with reasonable confidence to aid the understanding of the suspension performance. Physiological results, mechanical measurements and simulation results all indicate that the full suspension bicycle shows a significant improvement in terms of comfort and energy expenditure when riding over regular bumps. The good correlation between measurement and simulation provides a tool that can be used in future for optimization of bicycle suspension design.