Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ripples

Sortuj według:

Ogranicz wyniki do:

The interpretative significance of ripple-derived sedimentary structures within an upper Neogene fluvial succession of central Poland

Maciaszek Piotr, Chomiak Lilianna, Wachocki Robert, Widera Marek

Geologos

2019

Vol. 25, No. 1

1--13

Sedimentary structures discussed in the present study are genetically linked to ripples that consist of pure sand or alternating sand and mud layers. All types of ripple-related structures, such as climbing-ripple cross-lamination and heterolithic bedding, i.e., flaser, wavy and lenticular (nodular), have been identified for the first time in fluvial strata that have been characterised previously as commonly massive. These small-scale bedforms, produced by migrating ripples, have been documented in a fluvial channel of late Neogene age in central Poland. The abundance and co-occurrence of the structures discussed and their spatial distribution provide evidence of their formation under very low-energy conditions, when flow velocity changed markedly, but was often significantly less than 0.5 m/s. Therefore, these ripple-derived sedimentary structures are here recognised as typical of channel fills of an anastomosing river.

Evolution of microstructures on silicon induced by femtosecond laser with multiple pulses

Yuan D. Q., Zhou M., Lu D. Q., Xu J. T.

Optica Applicata

2011

Vol. 41, nr 3

727--734

The effect of multiple pulses of Ti:sapphire femtosecond laser system on silicon wafer was investigated. Using the pulse energy exceed the threshold of silicon to investigate the evolvement of structures and found that exceed certain fluence no any periodic structure will appearance. For 1.91 J/cm2, the pattern of columnar structure was formed in the central region of irradiation area. In further experiment, using the subthreshold multiple pulse femtosecond laser irradiation of 0.91 J/cm2, the periodic ripple structures and nanohole array were presented in the whole irradiation area due to the incubation effection. Also, we obtained the threshold of nanohole array to be higher than that of the periodic ripple structures.