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. The flyer for the event can be downloaded by clicking on the blue download button

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 Cu$_x$Bi$_2$Se$_3$ 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