Analyzing and simulating supply chain disruptions to the automobile industry based on experiences of the Great East Japan Earthquake

The Great East Japan Earthquake revealed serious weaknesses in the supply chain management (SCM) employed by Japanese industries, and particularly by the automobile industry. Observed supply chain disruptions and production line shutdowns are recognized as symbolic of weaknesses in industrial SCM. The Japanese automobile industry in particular is now keen to improve supply chain resiliency in terms of automobile assembly line continuity. In view of this, we i) review observed negative impacts of the Great East Japan Earthquake on the automobile industry, ii) identify current strategies being evaluated by the automobile industry for improving supply chain resiliency, iii) develop a numerical supply chain model for the automobile industry, and iv) evaluate efforts to improve SCM practice through inclusion of risk mitigation measures. We conclude with recommendations for policy development to further strengthen automobile industry resiliency

Evolution of Galactic Outflows at z∼0z\sim0-22 Revealed with SDSS, DEEP2, and Keck spectra

We conduct a systematic study of galactic outflows in star-forming galaxies at $z\sim0$-$2$ based on the absorption lines of optical spectra taken from SDSS DR7, DEEP2 DR4, and Keck Erb et al. We carefully make stacked spectra of homogeneous galaxy samples with similar stellar mass distributions at $z\sim0$-$2$, and perform the multi-component fitting of model absorption lines and stellar continua to the stacked spectra. We obtain the maximum (v_\rm{max}) and central (v_\rm{out}) outflow velocities, and estimate the mass loading factors ($\eta$), a ratio of the mass outflow rate to the star formation rate (SFR). Investigating the redshift evolution of the outflow velocities measured with the absorption lines whose depths and ionization energies are similar (Na I D and Mg I at $z\sim0$-$1$; Mg II and C II at $z\sim1$-$2$), we identify, for the first time, that the average value of v_\rm{max} (v_\rm{out}) significantly increases by 0.05-0.3 dex from $z\sim0$ to $2$ at a given SFR. Moreover, we find that the value of $\eta$ increases from $z\sim0$ to $2$ by $\eta \propto (1 + z)^{1.2\pm0.3}$ at a given halo circular velocity v_\rm{cir} , albeit with a potential systematics caused by model parameter choices. The redshift evolution of v_\rm{max} (v_\rm{out}) and $\eta$ is consistent with the galaxy-size evolution and the local velocity-SFR surface density relation, and explained by high-gas fractions in high-redshift massive galaxies, which is supported by recent radio observations. We obtain a scaling relation of \eta \propto v_\rm{cir}^a for $a = -0.2 \pm 1.1$ in our $z\sim0$ galaxies that agrees with the momentum-driven outflow model ($a = -1$) within the uncertainty.Comment: 13 pages, 10 figures, ApJ in pres