http://apps.eui.eu/Personal/Canova/Articles/similarities.pdf

Similarities and convergence in G-7 cycles

This paper examines the properties of G-7 cycles using a multicountry Bayesian panel VAR model with time variations, unit specific dynamics and cross country interdependences. We demonstrate the presence of a significant world cycle and show that country specific indicators play a much smaller role. We detect di erences across business cycle phases but, apart from an increase in synchronicity in the late 1990s, find little evidence of major structural changes. We also find no evidence of the existence of an Euro area specific cycle or of its emergence in the 1990s.

LOWNDES, ERIK MCKENZIE. Development of an Intermediate DOF Vehicle Dynamics Model for Optimal Design Studies. (Under the direction of Dr. Joseph W. David) The demands imposed by the optimal design process form a unique set of criteria for the development of a computational model for vehicle simulation. Due to the large number of simulations that must be performed to obtain an optimized design the model must be computationally efficient. A competing criterion is that the computational model must realistically model the vehicle. Current trends in vehicle simulation codes have tackled the problem of realism by constructing elaborate full vehicle models containing dozens if not hundreds of distinct bodies. Each body in a model of this type is associated with six degrees of freedom. Numerous constraint equations are applied to the bodies to represent the physical connections. While the formulation of the equations is not particularly difficult, and in fact has been automated in several software packages, the resulting model requires a considerable amount of computational time to run. This makes the model unsuitable for the application of computational optimal design techniques. Past research in the field of vehicle dynamics has produced numerous computational models which are small enough and fast enough to satisfy the speed demands of the optimal design process. These models typically use less than a dozen degrees of freedom to model the vehicle. They do a good job of predicting the general motion of the vehicle and they are useful as design tools but they lack the accuracy required for optimal design. A model that bridges the gap between these two existing classes of models and is suitable for performing optimal design was developed. The model possesses twenty-eight degrees of freedom and consists of eight bodies which represent the sprung mass, the rear suspension, the left front spindle, the right front spindle, and the four wheels. A driver control algorithm was developed which is capable of driving the car near its handling limits. The NCSU Legends race car was modeled and an attempt was made to optimize the vehicle setup for the Kenley, NC race track. Development of an Intermediate DOF Vehicle Dynamics Model for Optimal Design Studies

Development of an Intermediate DOF Vehicle Dynamics Model for Optimal Design Studies

This thesis deals with the development of advanced mathematical models for the assessment of the influence of chassis flexibility on vehicle handling qualities. A review of the literature relevant to the subject is presented and discussed in the first part of the thesis. A preliminary model that includes chassis flexibility is then developed and employed for a first assessment of the significance of chassis flexibility. In the second part of the thesis a symbolic multibody library for vehicle dynamics simulations is introduced. This library constitutes the basis for the development of an advanced 14-degrees-of-freedom vehicle model that includes chassis flexibility. The model is then demonstrated using a set of data relative to a real vehicle. Finally, simulation results are discussed and conclusions are presented. The advanced model fully exploits a novel multibody formulation which represent the kinematics and the dynamics of the system with a level of accuracy which is typical of numeric multibody models while retaining the benefits of purpose-developed handderived models. More specifically, a semi-recursive formulation, a velocity projection technique and a symbolic development are, for the first time, coupled with flexible body modelling. The effect of chassis flexibility on vehicle handling is observed through the analysis of openand closed-loop manoeuvres. Results show that chassis flexibility induces variations of lateral load transfer distribution and suspension kinematics that sensibly affect the steady-state behaviour of the vehicle. Further effects on dynamic response and high-speed stability are demonstrated. Also, optimal control theory is employed to demonstrate the existence of a strict correlation between chassis flexibility and driver behaviour. The research yields new insights into the dynamics of vehicles with a flexible chassis and highlights critical aspects of chassis design. Although the focus is on sports and race cars, both the modelling approach and the results can be extended to other vehicles.

Modelling chassis flexibility in vehicle dynamics simulation

This paper presents an overview of the evolution of computer simulations in vehicle collision and occupant kinematic reconstructions. The basic principles behind these simulations, the origin of these programs and the evolution of these programs from a basic analytical mathematical model to a sophisticated computer program are discussed. In addition, a brief computer development history is discussed to demonstrate how the evolution of computer assisted vehicle accident reconstruction becomes feasible for a reconstructionist. Possible future research in computer reconstruction is also discussed.

R.L. Code

Papers

A hybrid simulation of vehicle dynamics and subsystems