15,297 research outputs found
CHEMICAL AND PHYSICAL CHARACTERISTICS OF M. PSOAS MAIOR FROM ALENTEJANO PIGS AT A VARIOUS LIVE WEIGTHS
The present study was carried out to investigate the evolution of biochemical composition and physical traits of the chemical composition and physical characteristics of muscle Psoas major (PM adipose during growth of Alentejano pigs
Retroreflecting curves in nonstandard analysis
We present a direct construction of retroreflecting curves by means of Nonstandard Analysis. We construct non self-intersecting curves which are of class C(1), except for a hyper-finite set of values, such that the probability of a particle being reflected from the curve with the velocity opposite to the velocity of incidence, is infinitely close to 1. The constructed curves are of two kinds: a curve infinitely close to a straight line and a curve infinitely close to the boundary of a bounded convex set. We shall see that the latter curve is a solution of the problem: find the curve of maximum resistance infinitely close to a given curve.CEOCFCTFEDER/POCT
Dynamic analysis of the train-bridge interaction: an accurate and efficient numerical method
The dynamic behavior of railway bridges carrying high-speed trains can be analyzed with or
without the consideration of the vehicle's own structure. However, due to the amount of
kinetic energy carried at high speeds, the train may interact significantly with the bridge,
especially when resonance occurs. Equally important is the riding comfort and the stability of
the track and train cars, which are usually the most critical limit states in the design of this
type of structures. With the aim of studying this problem a computer code was developed,
being the interaction between the bridge and the train implemented by means of contact
conditions between each train wheel (nodal point) and the structure (point inside a finite
element). The treatment of the interaction between a train wheel and a point on the surface of
a finite element is directly and efficiently implemented by means of an extended stiffness
matrix, which includes stiffness, flexibility and additional terms that stem from the
compatibility equations between the displacements of the vehicle and the bridge. This
methodology was applied to the study of the dynamic behavior of a bowstring arch bridge and
proved to be very accurate and efficien
Development of an efficient finite element model for the dynamic analysis of the train-bridge interaction
The design of high-speed railway bridges comprises a set of demands, from safety
and serviceability aspects, to new types of equipment and construction solutions. In order to perform
an accurate and realistic evaluation of the corresponding dynamic behavior, adequate
analysis tools that take into account the complexity of the train-bridge system are required.
These computational tools must be based on efficient algorithms to allow for the completion of
detailed dynamic analyses in a reasonable amount of time. The classical methods of analysis
may be unsatisfactory in the evaluation of the dynamic effects of the train-bridge system and
fully assessment of the structural safety, track safety and passenger comfort. A direct and versatile
technique for the simulation of the train-bridge interaction was implemented in the FEMIX
code, which is a general purpose finite element computer program. The presented case study is
an application of the proposed formulation, which proved to be very accurate and efficient
- …