Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surfac...Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.展开更多
In this article we investigate the uniformity of direct union of k copies of Chord which is an improvedversion of Chord P2P system. We are interested in the maximal and the minimal areas controlled by nodes inthe syst...In this article we investigate the uniformity of direct union of k copies of Chord which is an improvedversion of Chord P2P system. We are interested in the maximal and the minimal areas controlled by nodes inthe system. We recall that the function n→k/k!.n-（1＋1/k）is a lower threshold and that the function n→1/n In（nlnk-k（n（k-1）1）/（k-1）1is an upper threshold for sizes of areas controlled by nodes in the direct union of kcopies of Chord.展开更多
文摘Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.
基金Supported by grant nr 2013/S30028 of the Institute of Mathematics and Computers Science of the Wrocaw University of Technology,Poland
文摘In this article we investigate the uniformity of direct union of k copies of Chord which is an improvedversion of Chord P2P system. We are interested in the maximal and the minimal areas controlled by nodes inthe system. We recall that the function n→k/k!.n-（1＋1/k）is a lower threshold and that the function n→1/n In（nlnk-k（n（k-1）1）/（k-1）1is an upper threshold for sizes of areas controlled by nodes in the direct union of kcopies of Chord.
