From outside-in to inside-out: galaxy assembly mode depends on stellar mass

In this Letter, we investigate how galaxy mass assembly mode depends on stellar mass $M_{\ast}$, using a large sample of $\sim$10, 000 low redshift galaxies. Our galaxy sample is selected to have SDSS R_{90}>5\arcsec.0, which allows the measures of both the integrated and the central NUV$-r$ color indices. We find that: in the $M_{\ast}-($ NUV$-r$) green valley, the M_{\ast}<10^{10}~M_{\sun} galaxies mostly have positive or flat color gradients, while most of the M_{\ast}>10^{10.5}~M_{\sun} galaxies have negative color gradients. When their central $D_{n}4000$ index values exceed 1.6, the M_{\ast}<10^{10.0}~M_{\sun} galaxies have moved to the UV red sequence, whereas a large fraction of the M_{\ast}>10^{10.5}~M_{\sun} galaxies still lie on the UV blue cloud or the green valley region. We conclude that the main galaxy assembly mode is transiting from "the outside-in" mode to "the inside-out" mode at M_{\ast} 10^{10.5}~M_{\sun}. We argue that the physical origin of this is the compromise between the internal and the external process that driving the star formation quenching in galaxies. These results can be checked with the upcoming large data produced by the on-going IFS survey projects, such as CALIFA, MaNGA and SAMI in the near future.Comment: Accepted for publication in ApJL,6 pages, 5 figure

STUDY ON INNOVATION AND MANAGEMENT OF THE OBJECTIVE STAGE IN PRODUCT DESIGN

In this paper, innovation and management during the objective stage of the product design process are studied. The idea of innovation for the whole product concept at the objective design stage was put forward in view of the overall development trends and mode of product design. The strategies of product innovation as well as its related process are also discussed. Finally, some recommendations regarding diminishing uncertainty in this stage of product design process are being made

The preparation and properties of novel structural carbon foams derived from different mesophase pitches

As a novel porous multi-functional carbon material, carbon foams have high bulk thermal conductivity and low density, making them as excellent materials for thermal management systems applications, such as heat exchangers, space radiators, and thermal protection systems. In this paper, the carbon foams with high thermal conductivity, derived from three kinds of mesophase pitches, were fabricated by the process of foaming, carbonization and graphitization. The microstructures of the foams were examined by scanning electron microscopy. It was found that the pores were uniformly distributed, and the pore wall thickened with increasing foams’ density. The properties of the foams were studied, including compressive strength and thermal conductivity. The results showed that lower density and higher thermal conductivity were achieved for the foams using the two kinds of pitches with higher volatile components. The bulk thermal conductivity of carbon foams were up to 179 W/(m·K) and 201 W/(m·K), for the densities of 0.66 g/cm3 and 0.83 g/cm3, respectively. The foams’ compressive strength was in the range of 1.6 MPa to 3.4 MPa

Giant Asymmetric Radiation from an Ultrathin Bianisotropic Metamaterial

Unidirectional radiation is of particular interest in high-power lasing and optics. Commonly, however, it is difficult to achieve a unidirectional profile in such a system without breaking reciprocity. Recently, assisted by metamaterials without structural symmetry, antennas that radiate asymmetrically have been developed, hence providing the possibility of achieving unidirectionality. Nevertheless, it has been challenging to achieve extremely high radiation asymmetry in such antennas. Here, we demonstrate that this radiation asymmetry is further enhanced when magnetic plasmons are present in the metamaterials. Experimentally, we show that a thin metamaterial with a thickness of approximately {\lambda}_0/8 can exhibit a forward-to-backward emission asymmetry of up to 1:32 without any optimization. Our work paves the way for manipulating asymmetric radiation by means of metamaterials and may have a variety of promising applications, such as directional optical and quantum emitters, lasers, and absorbers.Comment: 22pages, 5figures, Journal Articl