10-GHz broadband optical frequency comb generation at 1550/1310 nm

The generation of high-repetition rate(frep≥10 GHz)ultra-broadband optical frequency combs(OFCs)at 1550 nm and 1310 nm is investigated by seeding two types of highly nonlinear fibers(HNLFs)with 10 GHz picosecond pulses at the pump wavelength of 1550 nm.When pumped near the zero dispersion wavelength(ZDW)in the normal dispersion region of a HNLF,10 GHz flat-topped OFC with 43 nm bandwidth within 5 dB power variation is generated by self-phase modulation(SPM)-based OFC spectral broadening at 26.5 dBm pump power,and 291 fs pulse trains with 10 GHz repetition rate are obtained at 18 dBm pump power without complicated pulse shaping methods.Furthermore,when pumped in the abnormal dispersion region of a HNLF,OFCs with dispersive waves around 1310 nm are studied using a common HNLF and fluorotellurite fibers,which maintain the good coherence of the pump light at 1550 nm.At the same time,sufficient tunability of the generated dispersive waves is achieved when tuning the pump power or ZDW.

Optimization approach hydroforming car beam billets based grey system theory

Perfect combination of structural size parameters of the hydroforming billets is essential to obtain even wall thicknesses of the car beam. Finite element （ FE ） analysis on hydroforming car beam was carried out, and the results were optimized according to multiple quality objectives by the grey system theory. With bending angle, bending radius and hight difference along the axis direction as variables, orthogonal FE analyses were conducted and the minimum and maximum wall thicknes ses of the billets with different sizes were obtained. Taking the minimum and maximum wall thick nesses as two references, the correlation coefficient between the data for reference and those for comparison by the grey system theory reduced multi objectives to a single quality objective, and the average correlation level of every billet facilitated the optimization of size parameters for hydroform ing car beam. The trial production showed that the optimization approach satisfied the need of hy droforming car beams.

High-g Impact Resistance for Epoxy Molding Compound

The behavior of resistance high-g impact of EMC （epoxy molding compound） with two package models, small outline package （POS） and Globtop, was evaluated by experimental method used Hopkinson bar. At 120,000 g （generated in the Hopkinson bar with widths about 70 μs） no damage in either the POS devices or the Globtop devices was observed. In order to enhance the EMC＇s ability of resistance high-g impact, buffering effect of epoxy resin was also studied. The experimental results above all show that EMC has a better performance of impact resistance at about 120,000 g, and epoxy resin can absorb the stress wave to have the protected ability. The study of this paper could serve as a basis for selection packaging materials and enhance its reliability in high-g impact environment.