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Efektywna prędkość kolei na świecie na średnich dystansach na początku 2018 roku

Wesołowski J.

TTS Technika Transportu Szynowego

2018

R. 25, nr 7-8

46--60

Z punktu widzenia pasażera kluczowym elementem mającym wpływ na wybór środka transportu jest czas podróży. Czas podróży jest pochodną rzeczywistej prędkości, jaka jest osiągana na danej trasie. Z różnych przyczyn kształtowania się sieci kolejowej, historycznych, ruchowych i handlowych, trasy pociągów nie przebiegają prostoliniowo pomiędzy punktem wyjściowym a celem podróży. Powoduje to wydłużenie trasy pociągu i ma wpływ na zmniejszenie rzeczywistej efektywnej prędkości pociągu, co przekłada się na wydłużenie czasu podróży. W artykule dokonana została analiza wybranych systemów transportowych na świecie z punktu widzenia ich efektywności mierzonej efektywną prędkością handlową pociągów. Wnioski z tych analiz mogą wykorzystywane przy planowaniu restrukturyzacji istniejących systemów transportowych oraz budowy nowych.

This is a speed survey of 150 train links selected from almost every country in world where railway passenger service exists, being it a network or a single line. Speed shown in Table 1 is related to direct geographical distance between origin and destination, and the resulting velocity is called „effective speed” (prędkość efektywna). It is believed to be justified by possible air competition, as cases were intentionally selected only of they refer to a distance range in the area of 500 km. This was reasonably adjusted to the geographical scale of a country – e.g. Israel or Ireland have it shorter, while Kazakhstan – longer. It is also deemed 500 km is probably on one hand the longest for a one-day trip to be served by railway (with 160 km as effective speed), and on the other a relatively common intercity distance for many non-European countries. Effective speed also shows the technological and operational skill of the railway in the same time as the maturity of its network of lines. For the core of Europe proper, as this table shows, it is still the unachieved challenge to superimpose genuine high speed on the local railway networks, even if they have had a substantial high-speed element already present for decades. It is suggested that in the pursue of remedy, it may be worth to look at Chinese experience. There is a strong need to rejuvenate the pace of the continent’s integration if transport is to become more ‘sustainable’ and Europe to remain an important element in the changing world. Great role can be placed on the overnight sleeper services able to serve distances in the range of 1 000 km already at classic mainline speeds. When high speed could once be involved, the range would grow to 2 250 km, virtually covering the whole continent. This paper also aims to analyze the role of elongation in design and practice as well as its impact on effective speed. And, last but not least, it was written to show the current state of the railway worldwide, the state extremely uneven after half a century of car and air domination and, as it is believed, at the threshold of the second era of railway growth.

Surface effects on the wave propagation in composites with random dispersive parallel cylindrical nanofibers

Kong Z., Qiang F. W., Wei P. J., Tang Q.

Archives of Mechanics

2015

Vol. 67, nr 5

355--370

The propagation of elastic waves in composites with randomly distributed parallel cylindrical nanofibers is studied. The non-classical boundary conditions on the surface of nanofibers are derived by using the surface elasticity theory. The scattering waves from an individual nanofiber are obtained by the plane-wave expansion method. These scattering waves from all nanofibers are summed up to obtain the multiple-scattering waves. The effective propagation constants (speed and attenuation) of coherent waves and the associated effective dynamical moduli of composites are evaluated numerically. Based on these numerical results, the influences of the surface effects on the effective dynamical properties of composites are discussed.