Modelling the Dynamics of a Three-wheeled Racecar: A Pilot Study to Establish the Feasibility of Developing a ‘Delta’ Configuration Performance Car

This paper presents a preliminary study of the dynamics of a ‘delta’ configuration three-wheeled sports car, based on a Reliant Robin chassis. Stiffness and damping values to give this vehicle ‘sporty’ ride dynamics have been proposed. Other dynamic qualities such as rollover and steady-state cornering have also been investigated, and then verified using Carmaker® simulation software. The car performs far better than the Robin in steady-state analyses, but simulation indicates that transient maneuvers such as braked corners can still cause the vehicle to roll. Remedial actions such as lowering the center of gravity are suggested. However, much of the data used in these analyses is assumed, and should be updated as the design progresses. Since the standard calculations used in this report are intended for four-wheeled vehicles, there is scope to develop a more detailed transient model to fully describe the unique dynamics of three-wheeled vehicles and develop design guidelines more suited to them

Modelling & analysis of hybrid dynamic systems using a bond graph approach

Hybrid models are those containing continuous and discontinuous behaviour. In constructing dynamic systems models, it is frequently desirable to abstract rapidly changing, highly nonlinear behaviour to a discontinuity. Bond graphs lend themselves to systems modelling by being multi-disciplinary and reflecting the physics of the system. One advantage is that they can produce a mathematical model in a form that simulates quickly and efficiently. Hybrid bond graphs are a logical development which could further improve speed and efficiency. A range of hybrid bond graph forms have been proposed which are suitable for either simulation or further analysis, but not both. None have reached common usage. A Hybrid bond graph method is proposed here which is suitable for simulation as well as providing engineering insight through analysis. This new method features a distinction between structural and parametric switching. The controlled junction is used for the former, and gives rise to dynamic causality. A controlled element is developed for the latter. Dynamic causality is unconstrained so as to aid insight, and a new notation is proposed. The junction structure matrix for the hybrid bond graph features Boolean terms to reflect the controlled junctions in the graph structure. This hybrid JSM is used to generate a mixed-Boolean state equation. When storage elements are in dynamic causality, the resulting system equation is implicit. The focus of this thesis is the exploitation of the model. The implicit form enables application of matrix-rank criteria from control theory, and control properties can be seen in the structure and causal assignment. An impulsive mode may occur when storage elements are in dynamic causality, but otherwise there are no energy losses associated with commutation because this method dictates the way discontinuities are abstracted. The main contribution is therefore a Hybrid Bond Graph which reflects the physics of commutating systems and offers engineering insight through the choice of controlled elements and dynamic causality. It generates a unique, implicit, mixed-Boolean system equation, describing all modes of operation. This form is suitable for both simulation and analysis

Specific antenatal interventions for Black, Asian and Minority Ethnic (BAME) pregnant women at high risk of poor birth outcomes in the United Kingdom: a scoping review

Background: Disparity exists in maternal and infant birth outcomes of Black and Minority Ethnic (BAME) women giving birth in the United Kingdom (UK) compared to the majority. There is therefore a need to reconsider existing maternity service provision to ensure culturally competent services. The purpose of this scoping review was to ascertain what specific maternity interventions have been implemented in the UK for BAME women (2004–2014) so that increased awareness of the need and scope of specific maternity interventions for BAME women can be identified. Methods: A scoping review was conducted in order to determine the evidence base. It was determined that no prior systematic reviews had been conducted and it was apparent that literature in this field was sparse. Scoping review is an ideal method when literature is likely to be heterogeneous and the research field relatively unexplored. A keyword strategy was used implementing population (P), intervention (I), comparison (C) and outcomes (O). Results: An initial 2188 papers were identified. Following screening and review, only 5 heterogeneous papers remained suitable and were included. The included interventions employed sample sizes of N = 160-1441, examined a range of different outcome measures and were delivered across different parts of the UK with high numbers of BAME residents. Conclusions: There is a lack of rigorous research interventions and practice interventions which are currently documented, of specific maternity interventions which are aimed to address culturally competent maternity services and the sharing of best practice addressing the increased risks of BAME women delivering in the UK

Organisational solutions for overcoming barriers to eGovernment

Citation: Eynon, R. & Margetts, H. (2007). 'Organisational solutions for overcoming barriers to eGovernment', European Journal of ePractice, 1: 6. This article is subject to a Creative Commons Attribution - Noncommercial - No Derivative Works 2.5 licence. It may be copied, distributed and broadcast provided that the authors and the European Journal of ePractice are cited. Commercial use and derivative works are not permitted. The full licence can be consulted at http://creativecommons.org/licenses/by-nc-nd/2.5

Comparison of modeling techniques for a landing gear

A wide range of modeling techniques is available to the engineer. The objective of this paper is to compare some typical modeling techniques for the simulation of a multidomain mechatronic system. Usual dynamic modeling methods, such as block diagrams and iconic diagrams, can cause problems for the engineer. Differential algebraic equations (DAEs) and algebraic loops can significantly increase simulation times and cause numeric errors. Bond graphs are less common in industry, and are presented here as a method which allows the engineer to easily identify causal loops and elements in differential causality. These can indicate DAEs in the underlying equations. An aircraft landing gear is given as an example of a multi-domain system, and is modeled as a block diagram, an iconic diagram and as a bond graph. The time to construct the model, time to solve and problems faced by the analyst are presented. Bond graphs offer distinct advantages in terms of the ease of implementing algebraic equations and visibility of causality. The time taken to model a system can be significantly reduced and the results appear free from computational errors. Bond graphs are therefore recommended for this type of multi-domain systems analysi

Modelling a drop test of a landing gear using a hybrid bond graph

A landing gear is a good example of a highly nonlinear multidisciplinary system. Using hybrid modelling, nonlinear behaviour can be abstracted to discontinuous behaviour. Bond graphs are an established and intuitive method for constructing mathematical models of multiphysics dynamic systems. The Hybrid Bond Graph is therefore used here to demonstrate the modelling of a landing gear drop test. A distinction is drawn between structural and parametric discontinuities, represented using controlled junctions and elements. Causally static and dynamic bond graphs are compared. A mixed Boolean mathematical model is obtained from the causally dynamic graph

Crossing two types of implementation intentions with a protection motivation intervention for the reduction of saturated fat intake: A randomized trial.

Implementation intentions, namely specific plans regarding when, where and how an individual will act, increase the likelihood of action. There is evidence that implementation intentions should be particularly efficacious when combined with motivational interventions. However, this is yet to be tested in relation to the reduction of unhealthy behaviour. Thus the aim of this study was to examine the efficacy of combined motivation and implementation intention interventions for the reduction of saturated fat intake. It also tested a new form of implementation intention (reasoning implementation intentions). Participants from the UK (n = 210) were randomized to condition and asked either to form standard implementation intentions, reasoning implementation intentions, or received no implementation intention manipulation; and were exposed to protection motivation-based information, or not. Results showed that standard and reasoning implementation intentions were successful in reducing the proportion of food energy derived from saturated fat but the effects of the standard implementation intention were dependent on whether participants read the motivational message or not