371 research outputs found
Longitudinal optical conductivities for tilted Weyl fermions in arbitrary dimensionality
The unified form of longitudinal optical conductivities (LOCs) for tilted
Weyl fermions in arbitrary spatial dimensionality is analytically calculated
and expressed in terms of the joint density of state. The results are valid for
both undoped and doped cases, both parallel and perpendicular components with
respect to the tilting direction, and all the tilted phases. In addition, they
automatically reproduce the analytical results of previous works for
one-dimensional, two-dimensional, and three-dimensional tilted Weyl systems.
Our work provides not only a once-for-all method prior to the one-by-one
calculation of LOCs but also deep insights into the impacts of spatial
dimensionality in the tilted Weyl fermions.Comment: 4 pages, no figure
Investigation and Experiment on a Short Dump-Diffuser of the Combustor
ABSTRACT This paper is intended to introduce optimal geometrical parameter matching obtained by using water flow simulation on the box-type specimen and blasting tests on the sector-type specimen for the short dump-diffuser of an annular combustion chamber, sad some special problems occurring in practice, such as, the effects of the factors --the head of flame tube,inlet cap, inlet support strut, splitting flow cone, air drawn from the wall surface and inlet velocity profiles on diffuser performance and its flow status, the obtained results provide the foundation for its practical application
Longitudinal optical conductivities in tilted Dirac bands
We report a unified theory based on linear response, for analyzing the
longitudinal optical conductivity (LOC) of materials with tilted Dirac cones.
Depending on the tilt parameter , the Dirac electrons have four phases,
untilted, type-I, type-II, and type-III; the Dirac dispersion can be isotropic
or anisotropic; the spatial dimension of the material can be one-, two-, or
three-dimensions. The interband LOCs and intraband LOCs in dimension (with
) are found to scale as to and
, respectively, where is the
frequency and the chemical potential. The interband LOCs always vanish in
one dimension due to lacking of extra spatial dimension. The angular dependence
of LOCs is found to characterize the band tilting, and the constant asymptotic
background values of LOC reflect features of the Dirac bands. The LOCs in the
anisotropic tilted Dirac cone can be connected to its isotropic counterpart by
a ratio that consists of Fermi velocities. The findings are valid for a great
many Dirac materials in the spatial dimensions of physical interests.Comment: 11 pages, 3 figure
Media Literasi: Upaya Bijak Menyikapi Terpaan Tayangan Televisi
The television media have transformed into industry. Tight competition among TV stations demands the media people to provide programs based on the market taste. Therefore, mostly TV stations design and produce their programs based on share and rating numbers, instead of quality. On the other side, TV stations have important roles in constructing social and cultural development. Currently, TV programs are merely produced based on the business orientation so that the quality of the TV programs is often ignored. Audience must be wise and smart to protect themselves from poor-quality TV programs exposure. This can be achieved by improving their Media Literacy. In the end, Audience is no longer treated as passive object, but actively takes control on the content selection
The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap I. The Spectroscopic Redshift Catalog
We present a spectroscopic redshift catalog from the LAMOST Complete
Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap
(SGC), which is designed to observe all sources (Galactic and extra-galactic)
by using repeating observations with a limiting magnitude of in
two fields. The project is mainly focusing on the completeness of
LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source
selection methods and the basic performance parameters of LAMOST telescope. In
both fields, more than 95% of galaxies have been observed. A post-processing
has been applied to LAMOST 1D spectrum to remove the majority of remaining sky
background residuals. More than 10,000 spectra have been visually inspected to
measure the redshift by using combinations of different emission/absorption
features with uncertainty of . In total, there are 1528
redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570
redshifts (569 absorption and 1001 emission line galaxies) in Field B have been
measured. The results show that it is possible to derive redshift from low SNR
galaxies with our post-processing and visual inspection. Our analysis also
indicates that up to 1/4 of the input targets for a typical extra-galactic
spectroscopic survey might be unreliable. The multi-wavelength data analysis
shows that the majority of mid-infrared-detected absorption (91.3%) and
emission line galaxies (93.3%) can be well separated by an empirical criterion
of . Meanwhile, a fainter sequence paralleled to the main population
of galaxies has been witnessed both in / and /
diagrams, which could be the population of luminous dwarf galaxies but
contaminated by the edge-on/highly inclined galaxies ().Comment: 19 pages, 14 figures, 2 MRT, accepted by ApJ
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