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81.
A Motorcycle Tire Model for Dynamic Simulations: Theoretical and Experimental Aspects 总被引:1,自引:0,他引:1
This paper describes a model for motorcycle tires based on a physical interpretation of experimental data. In this model the real shape of the tire carcass is accurately described and its deformability is taken into account. The actual position of the contact point, that is, the center of the contact patch, is calculated. The concept of instantaneous slip is defined by calculating the longitudinal slip and sideslip angles using the velocity of the actual contact point, which moves with respect to the rim. Tire forces and torques are applied on the actual contact point and calculated according to Pacejkas magic formula. The coupling of sliding properties with elastic ones and the use of the instantaneous slip concept make it possible to properly describe both steady state and transient behavior using the same relations, thus avoiding the use of any auxiliary equations. 相似文献
82.
Long-duration experiments with clouds of microparticles are planned for the ICAPS facility on board the International Space Station ISS. The scientific objectives of such experiments are widespread and are ranging from the simulation of aerosol behaviour in Earths atmosphere to the formation of planets in the early solar system. It is, however, even under microgravity conditions, impossible to sustain a cloud of free-floating, microscopic particles for an extended period of time, due to thermal diffusion and due to unavoidable external accelerations. Therefore, a trap for dust clouds is required which prevents the diffusion of the particles, which provides a source of relative velocities between the dust grains and which can also concentrate the dust to higher number densities that are otherwise not achievable. We are planning to use the photophoretic effect for such a particle trap. First short-duration microgravity experiments on the photophoretic motion of microscopic particles show that such an optical particle-cloud trap is feasible. First tests of a two-dimensional trap were performed in the Bremen drop tower. 相似文献
83.
Goujon C Thomas N Dalloz-Dubrujeaud B 《The European physical journal. E, Soft matter》2003,11(2):147-157
Recent studies have pointed out the importance of the
basal friction on the dynamics of granular flows. We present
experimental results on the influence of the roughness of the
inclined plane on the dynamics of a monodisperse dry granular
flow. We found experimentally that there exists a maximum of the
friction for a given relative roughness. This maximum is shown
to be independent of the slope angle. This behavior is observed
for four planes with different bump sizes (given by the size of
the beads glued on the plane) from 200 m to 2 mm. The relative
roughness corresponding to the maximum of the friction can be
predicted with a geometrical model of stability of one single
bead on the plane. The main parameters are the size of the bumps
and the size of the flowing beads. In order to obtain a higher
precision, the model also takes into account the spacing between
the bumps of the rough plane. Experimental results and model are
in good agreement for all the planes we studied. Other
parameters, like the sphericity of the beads, or irregularities
in the thickness of the layer of glued particles, are shown to
be of influence on the friction. 相似文献
84.
F. Crisciani R. Purini 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):571-575
The present note deals with Munk's ocean model and proposes an alternative approach to find its solution, with special regard
to the western boundary layer. We introduce a suitable “distance” between the related Sverdrup streamfunction and all the
admissible streamfunctions which are valid in the western boundary layer. We prove that such distance has a minimum that singles
out a unique solution. Unlike the traditional method, this procedure works without assuming a priori any dynamic boundary
condition.
Received 16 July 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: fulcri@itt.ts.cnr.it 相似文献
85.
H. A. Batarfi S. S. Hassan R. Saunders R. K. Bullough 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(3):417-429
Linear stability analysis and (numerical) investigation of the periodic and chaotic self-pulsing behaviour are presented for
the Maxwell-Bloch equations of a bistable model in contact with a squeezed vacuum field. Effect of the squeeze phase parameter
on the period doubling bifurcation that preceeds chaos is examined for the adiabatic and non-adiabatic regimes. 相似文献
86.
M. Ludwig P. Abell 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(1):97-105
Social networks in communities, markets, and societies self-organise through the interactions of many individuals. In this
paper we use a well-known
mechanism of social interactions — the balance of sentiment in triadic
relations — to describe the development of social networks. Our model
contrasts with many existing network models, in that people not only
establish but also break up relations whilst the network evolves. The
procedure generates several interesting network features such as a variety
of degree distributions and degree correlations. The resulting network
converges under certain conditions to a steady critical state where temporal
disruptions in triangles follow a power-law distribution. 相似文献
87.
介绍了EAST托卡马克逆磁线圈加补偿线圈的逆磁测量。该方法的优点是补偿线圈有效地消除了纵场线圈产生的磁通变化,而调节机构能降低来自极向场的误差信号。详细地叙述了逆磁线圈工程设计中考虑的材料选择和结构设计对逆磁线圈的影响。最后给出了次测量系统的误差分析。 相似文献
88.
Importance sampling Monte Carlo offers powerful approaches to approximating Bayesian updating in sequential problems. Specific classes of such approaches are known as particle filters. These procedures rely on the simulation of samples or ensembles of the unknown quantities and the calculation of associated weights for the ensemble members. As time evolves and/or when applied in high-dimensional settings, such as those of interest in many data assimilation problems, these weights typically display undesirable features. The key difficulty involves a collapse toward approximate distributions concentrating virtually all of their probability on an implausibly few ensemble members.
After reviewing ensembling, Monte Carlo, importance sampling and particle filters, we present some approximations intended to moderate the problem of collapsing weights. The motivations for these suggestions are combinations of (i) the idea that key dynamical behavior in many systems actually takes place on a low dimensional manifold, and (ii) notions of statistical dimension reduction. We illustrate our suggestions in a problem of inference for ocean surface winds and atmospheric pressure. Real observational data are used. 相似文献
89.
L. Wu S. Zhu Y. Ni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):349-354
Combination of two basic types of synchronization, anticipatory
synchronization and lagged synchronization, is investigated
numerically between two coupled semiconductor lasers. It is found
that lagged synchronization produced by a backward coupling with a
suitable delay can combine with the originally hidden anticipatory
synchronization and produce a type of synchronization overcoming the
original lagged synchronization produced by a forward coupling. We
study the combination synchronization phenomenon when the delay of
the backward coupling is different from that of the original
anticipatory synchronization. Our results suggest that the
synchronization combination phenomenon might allow an interpretation
of an experimental observation by Sivaprakasam et al. [Phys.
Rev. Lett. 87, 154101 (2001)] that the anticipating time is
irrespective of the external-cavity round trip time, which to date remains to be understood. 相似文献
90.
We analyse the structure and behaviour of a specific voting network using a dynamic structure-based methodology which draws on Q-Analysis and social network theory. Our empirical focus is on the Eurovision Song Contest over a period of 20 years. For a multicultural contest of this kind, one of the key questions is how the quality of a song is judged and how voting groups emerge. We investigate structures that may identify the winner based purely on the topology of the network. This provides a basic framework to identify what the characteristics associated with becoming a winner are, and may help to establish a homogenous criterion for subjective measures such as quality. Further, we measure the importance of voting cliques, and present a dynamic model based on a changing multidimensional measure of connectivity in order to reveal the formation of emerging community structure within the contest. Finally, we study the dynamic behaviour exhibited by the network in order to understand the clustering of voting preferences and the relationship between local and global properties. 相似文献