4,112 research outputs found
The whistler nozzle phenomenon
The whistler nozzle is a simple device which can induce jet self-excitations of controllable amplitudes and frequencies and appears highly promising for many applications involving turbulent transport, combustion and aerodynamic noise. The characteristics of this curious phenomenon are documented for different values of the controlling parameters and attempts to explain the phenomenon. It is shown that the whistler excitation results from the coupling of two independent resonance mechanisms: shear-layer tone resulting from the impingement of the pipe-exit shear layer on the collar lip, and organ-pipe resonance of the pipe-nozzle. The crucial role of the shear-layer tone in driving the organ-pipe resonance is proven by reproducing the event in pipe-ring and pipe-hole configurations in the absence of the collar. It is also shown that this phenomenon is the strongest when the self-excitation frequency matches the preferred mode of the jet
2D Carbon-based Device Design, Simulation and Electrical Characterization
Due to the scaling of the device dimension, device performance is getting limited day by day. Researchers are facing new challenges in quest of sustainable solutions in device architecture and material characterization. 2D carbon-based materials are posing outstanding electrical and thermal properties; novel materials can be exploited in the electrical transport mechanism by improving device architecture. Carbon and nanodiamond-based materials are characterized in MOSFET-type device architecture for further improvement. Besides, delta-doped silicon MOSFET is simulated to overcome the shortcomings in short channel effects.
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Rancang Bangun Sistem Informasi Pelayanan Angkutan Terminal Kota Pekanbaru Berbasis Online
Penggunaan teknologi dalam bidang komputer dewasa ini semakin meningkat, seiring dengan perkembangan ilmu pengetahuan dan globalisasi informasi yang menuntut terciptanya keadaan yang serba komputerisasi. Pada Dinas Perhubungan Kota Pekanbaru, khususnya pada Terminal Bandar Raya Payung Sekaki (BRPS) penyampaian informasi masih bersifat manual yang dicatat pada buku register dan nantinya akan diinputkan menggunakan program Microsoft excel. Tujuan Penelitian ini adalah memberikan gambaran perancangan sistem monitoring, retribusi dan penjadwalan mobil angkutan Perusahaan di Terminal Bandar Raya Payung Sekaki (BRPS) sehingga dapat membantu penyaluran informasi kepada masyarakat.Merancang sistem monitoring, retribusi dan penjadwalan mobil angkutan Perusahaan di Terminal Bandar Raya Payung Sekaki (BRPS) yang bersifat komputerisasi dan online.
Keywords; Perancangan, Aplikasi, Layanan, Dinas Perhubungan,Pelayanan, Pemerinta
Chemically gated electronic structure of a superconducting doped topological insulator system
Angle resolved photoemission spectroscopy is used to observe changes in the
electronic structure of bulk-doped topological insulator CuBiSe as
additional copper atoms are deposited onto the cleaved crystal surface. Carrier
density and surface-normal electrical field strength near the crystal surface
are estimated to consider the effect of chemical surface gating on atypical
superconducting properties associated with topological insulator order, such as
the dynamics of theoretically predicted Majorana Fermion vortices
Single-Dirac-Cone topological surface states in TlBiSe2 class of Topological Insulators
We have investigated several strong spin-orbit coupling ternary chalcogenides
related to the (Pb,Sn)Te series of compounds. Our first-principles calculations
predict the low temperature rhombohedral ordered phase in TlBiTe2, TlBiSe2, and
TlSbX2 (X=Te, Se, S) to be topologically Kane-Mele Z2 = -1 nontrivial. We
identify the specific surface termination that realizes the single Dirac cone
through first-principles surface state computations. This termination minimizes
effects of dangling bonds making it favorable for photoemission (ARPES)
experiments. Our analysis predicts that thin films of these materials would
harbor novel 2D quantum spin Hall states, and support odd-parity topological
superconductivity. For a related work also see arXiv:1003.2615v1. Experimental
ARPES results will be published elsewhere.Comment: Accepted for publication in Phys. Rev. Lett. (2010). Submitted March
201
Charge collective modes in an incommensurately modulated cuprate
We report the first measurement of collective charge modes of insulating
Sr14Cu24O41 using inelastic resonant x-ray scattering over the complete
Brillouin zone. Our results show that the intense excitation modes at the
charge gap edge predominantly originate from the ladder-containing planar
substructures. The observed ladder modes (E vs. Q) are found to be dispersive
for momentum transfers along the "legs" but nearly localized along the "rungs".
Dispersion and peakwidth characteristics are similar to the charge spectrum of
1D Mott insulators, and we show that our results can be understood in the
strong coupling limit (U >> t_{ladder}> t_{chain}). The observed behavior is in
marked contrast to the charge spectrum seen in most two dimensional cuprates.
Quite generally, our results also show that momentum-tunability of inelastic
scattering can be used to resolve mode contributions in multi-component
incommensurate systems.Comment: 4+ pages, 5 figure
Inelastic X-ray scattering in correlated (Mott) insulators
We calculate the inelastic light scattering from X-rays, which allows the
photon to transfer both energy and momentum to the strongly correlated charge
excitations. We find that the charge transfer peak and the low energy peak both
broaden and disperse through the Brillouin zone similar to what is seen in
experiments in materials like Ca_2 Cu O_2 Cl_2.Comment: 5 pages Revtex4, 6 figure
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