We introduce the LAMOST Stellar Parameter Pipeline at Peking University -LSP3, developed and implemented for the determinations of radial velocity V r and stellar atmospheric parameters (effective temperature T eff , surface gravity log g, metallicity [Fe/H]) for the LAM-OST Spectroscopic Survey of the Galactic Anti-center (LSS-GAC). We describe the algorithms of LSP3 and examine the accuracy of parameters yielded by it. The precision and accuracy of parameters yielded are investigated by comparing results of multi-epoch observations and of candidate members of open and globular clusters, with photometric calibration, as well as with independent determinations available from a number of external databases, including the PASTEL archive, the APOGEE, SDSS and RAVE surveys, as well as those released in the LAMOST DR1. The uncertainties of LSP3 parameters are characterized and quantified as a function of the spectral signal-to-noise ratio (SNR) and stellar atmospheric parameters. We conclude that the current implementation of LSP3 has achieved an accuracy of 5.0 km s −1 , 150 K, 0.25 dex, 0.15 dex for the radial velocity, effective temperature, surface gravity and metallicity, respectively, for LSS-GAC spectra of FGK stars of SNRs per pixel higher than 10. The LSP3 has been applied to over a million LSS-GAC spectra collected hitherto. Stellar parameters yielded by the LSP3 will be released to the general public following the data policy of LAMOST, together with estimates of the interstellar extinction E(B − V ) and stellar distances, deduced by combining spectroscopic and multi-band photometric measurements using a variety of techniques.

The microstructure of second-phase particles in the Ti-55 alloy was studied by scanning electron microscopy, transmission electron microscopy (TEM), and highresolution electron microscopy (HREM) observations. The second-phase particles in the conventional ingot-cast Ti-55 alloy of 1 to 15 m in diameter and uniform distribution in matrix were observed, where the majority of these particles are elliptical. The mean free path between the particles is about 46 m, and the volume fraction (pct) is 2.35. The second-phase particles typically contain Nd, Sn, and O in substantial amounts, and the content of Nd is the largest in the three elements. The elements Ti, Al, Zr, Mo and Si are depleted in the particles. The second-phase particle consists of either a dark or bright matrix and some small dark blocks dispersed within the matrix. Dark blocks match SnO (orthorhombic, a ϭ 0.500 nm, b ϭ 0.572 nm, and c ϭ 1.120 nm), and the matrix consists of a nanocrystalline phase with a stoichiometric Nd 3 Sn structure having a space group of Pm3m and lattice parameter of a ϭ 0.344 nm. The grain size of the nanocrystalline Nd 3 Sn phase is about 3 to 15 nm. The melting range of the second-phase particle is estimated to be 1042 ЊC to 1600 ЊC. The microstructure of the second-phase particles in the quenched Ti-55 alloy was also studied. Fine and uniform dispersoids (6 to 15 nm in diameter) were observed in the as-quenched state. Some lenslike particles occur at the grain boundaries, other elliptical particles appear within the grains, and some particles within the grains form rows which are parallel to the advancing liquid-solid interface. After annealing at 980 ЊC (1 to 10 hours), of the as-quenched Ti-55 alloy, coarse particles are 17 to 42 nm in average diameter, and the growth of the particles is very slow. The dispersoids in the asannealed Ti-55 alloy are identified as nanocrystalline Nd 5 Sn (orthorhombic, Pnmn, a ϭ 0.814 nm, b ϭ 1.732 nm, and c ϭ 0.814 nm) intermetallic compound, and the interface between the Nd 5 Sn 4 phase and the matrix is a typical high-angle grain boundary.

We have developed and implemented an iterative algorithm of flux calibration for the LAM-OST Spectroscopic Survey of the Galactic anti-center (LSS-GAC). For a given LSS-GAC plate, the spectra are first processed with a set of nominal spectral response curves (SRCs) and used to derive initial stellar atmospheric parameters (effective temperature T eff , surface gravity log g and metallicity [Fe/H]) as well as dust reddening E(B − V ) of all targeted stars. For each of the sixteen spectrographs, several F-type stars of good signal-to-noise ratios (SNRs) are then selected as flux standard stars for further, iterative spectral flux calibration. Comparison of spectrophotometric colours, deduced from the flux-calibrated spectra, with the photometric measurements yields average differences of 0.02±0.07 and −0.04±0.09 mag for the (g − r) and (g − i), respectively. The relatively large negative offset in (g − i) is due to the fact that we have opted not to correct for the telluric bands, most notably the atmospheric A-band in the wavelength range of i-band. Comparison of LSS-GAC multi-epoch observations of duplicate targets indicates that the algorithm has achieved an accuracy of about 10 per cent in relative flux calibration for the wavelength range 4000 -9000Å. The shapes of SRC deduced for the individual LAMOST spectrographs are found to vary by up to 30 per cent for a given night, and larger for different nights, indicating that the derivation of SRCs for the individual plates is essential in order to achieve accurate flux calibration for the LAMOST spectra.